dom/events/EventDispatcher.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/Assertions.h"
   8 #include "nsPresContext.h"
   9 #include "nsContentUtils.h"
  10 #include "nsDocShell.h"
  11 #include "nsError.h"
  12 #include <new>
  13 #include "nsIContent.h"
  14 #include "nsIContentInlines.h"
  15 #include "mozilla/dom/Document.h"
  16 #include "nsINode.h"
  17 #include "nsIScriptObjectPrincipal.h"
  18 #include "nsPIDOMWindow.h"
  19 #include "nsRefreshDriver.h"
  20 #include "AnimationEvent.h"
  21 #include "BeforeUnloadEvent.h"
  22 #include "ClipboardEvent.h"
  23 #include "CommandEvent.h"
  24 #include "CompositionEvent.h"
  25 #include "DeviceMotionEvent.h"
  26 #include "DragEvent.h"
  27 #include "KeyboardEvent.h"
  28 #include "mozilla/BasePrincipal.h"
  29 #include "mozilla/ContentEvents.h"
  30 #include "mozilla/dom/CloseEvent.h"
  31 #include "mozilla/dom/CustomEvent.h"
  32 #include "mozilla/dom/DeviceOrientationEvent.h"
  33 #include "mozilla/dom/EventTarget.h"
  34 #include "mozilla/dom/FocusEvent.h"
  35 #include "mozilla/dom/HashChangeEvent.h"
  36 #include "mozilla/dom/InputEvent.h"
  37 #include "mozilla/dom/MessageEvent.h"
  38 #include "mozilla/dom/MouseScrollEvent.h"
  39 #include "mozilla/dom/MutationEvent.h"
  40 #include "mozilla/dom/NotifyPaintEvent.h"
  41 #include "mozilla/dom/PageTransitionEvent.h"
  42 #include "mozilla/dom/PerformanceEventTiming.h"
  43 #include "mozilla/dom/PerformanceMainThread.h"
  44 #include "mozilla/dom/PointerEvent.h"
  45 #include "mozilla/dom/RootedDictionary.h"
  46 #include "mozilla/dom/ScrollAreaEvent.h"
  47 #include "mozilla/dom/SimpleGestureEvent.h"
  48 #include "mozilla/dom/ScriptSettings.h"
  49 #include "mozilla/dom/StorageEvent.h"
  50 #include "mozilla/dom/TextEvent.h"
  51 #include "mozilla/dom/TimeEvent.h"
  52 #include "mozilla/dom/TouchEvent.h"
  53 #include "mozilla/dom/TransitionEvent.h"
  54 #include "mozilla/dom/WheelEvent.h"
  55 #include "mozilla/dom/WorkerPrivate.h"
  56 #include "mozilla/dom/XULCommandEvent.h"
  57 #include "mozilla/EventDispatcher.h"
  58 #include "mozilla/EventListenerManager.h"
  59 #include "mozilla/InternalMutationEvent.h"
  60 #include "mozilla/ipc/MessageChannel.h"
  61 #include "mozilla/MiscEvents.h"
  62 #include "mozilla/MouseEvents.h"
  63 #include "mozilla/ProfilerLabels.h"
  64 #include "mozilla/ProfilerMarkers.h"
  65 #include "mozilla/ScopeExit.h"
  66 #include "mozilla/Telemetry.h"
  67 #include "mozilla/TextEvents.h"
  68 #include "mozilla/TouchEvents.h"
  69 #include "mozilla/Unused.h"
  70
  71 namespace mozilla {
  72
  73 using namespace dom;
  74
  75 class ELMCreationDetector {
  76  public:
  77   ELMCreationDetector()
  78       // We can do this optimization only in the main thread.
  79       : mNonMainThread(!NS_IsMainThread()),
  80         mInitialCount(mNonMainThread
  81                           ? 0
  82                           : EventListenerManager::sMainThreadCreatedCount) {}
  83
  84   bool MayHaveNewListenerManager() {
  85     return mNonMainThread ||
  86            mInitialCount != EventListenerManager::sMainThreadCreatedCount;
  87   }
  88
  89   bool IsMainThread() { return !mNonMainThread; }
  90
  91  private:
  92   bool mNonMainThread;
  93   uint32_t mInitialCount;
  94 };
  95
  96 static bool IsEventTargetChrome(EventTarget* aEventTarget,
  97                                 Document** aDocument = nullptr) {
  98   if (aDocument) {
  99     *aDocument = nullptr;
 100   }
 101
 102   Document* doc = nullptr;
 103   if (nsINode* node = nsINode::FromEventTargetOrNull(aEventTarget)) {
 104     doc = node->OwnerDoc();
 105   } else if (nsPIDOMWindowInner* window =
 106                  nsPIDOMWindowInner::FromEventTargetOrNull(aEventTarget)) {
 107     doc = window->GetExtantDoc();
 108   }
 109
 110   // nsContentUtils::IsChromeDoc is null-safe.
 111   bool isChrome = false;
 112   if (doc) {
 113     isChrome = nsContentUtils::IsChromeDoc(doc);
 114     if (aDocument) {
 115       nsCOMPtr<Document> retVal = doc;
 116       retVal.swap(*aDocument);
 117     }
 118   } else if (nsCOMPtr<nsIScriptObjectPrincipal> sop =
 119                  do_QueryInterface(aEventTarget->GetOwnerGlobal())) {
 120     isChrome = sop->GetPrincipal()->IsSystemPrincipal();
 121   }
 122   return isChrome;
 123 }
 124
 125 // EventTargetChainItem represents a single item in the event target chain.
 126 class EventTargetChainItem {
 127  public:
 128   explicit EventTargetChainItem(EventTarget* aTarget)
 129       : mTarget(aTarget), mItemFlags(0) {
 130     MOZ_COUNT_CTOR(EventTargetChainItem);
 131   }
 132
 133   MOZ_COUNTED_DTOR(EventTargetChainItem)
 134
 135   static EventTargetChainItem* Create(nsTArray<EventTargetChainItem>& aChain,
 136                                       EventTarget* aTarget,
 137                                       EventTargetChainItem* aChild = nullptr) {
 138     // The last item which can handle the event must be aChild.
 139     MOZ_ASSERT(GetLastCanHandleEventTarget(aChain) == aChild);
 140     MOZ_ASSERT(!aTarget || aTarget == aTarget->GetTargetForEventTargetChain());
 141     EventTargetChainItem* etci = aChain.AppendElement(aTarget);
 142     return etci;
 143   }
 144
 145   static void DestroyLast(nsTArray<EventTargetChainItem>& aChain,
 146                           EventTargetChainItem* aItem) {
 147     MOZ_ASSERT(&aChain.LastElement() == aItem);
 148     aChain.RemoveLastElement();
 149   }
 150
 151   static EventTargetChainItem* GetFirstCanHandleEventTarget(
 152       nsTArray<EventTargetChainItem>& aChain) {
 153     return &aChain[GetFirstCanHandleEventTargetIdx(aChain)];
 154   }
 155
 156   static uint32_t GetFirstCanHandleEventTargetIdx(
 157       nsTArray<EventTargetChainItem>& aChain) {
 158     // aChain[i].PreHandleEventOnly() = true only when the target element wants
 159     // PreHandleEvent and set mCanHandle=false. So we find the first element
 160     // which can handle the event.
 161     for (uint32_t i = 0; i < aChain.Length(); ++i) {
 162       if (!aChain[i].PreHandleEventOnly()) {
 163         return i;
 164       }
 165     }
 166     MOZ_ASSERT(false);
 167     return 0;
 168   }
 169
 170   static EventTargetChainItem* GetLastCanHandleEventTarget(
 171       nsTArray<EventTargetChainItem>& aChain) {
 172     // Fine the last item which can handle the event.
 173     for (int32_t i = aChain.Length() - 1; i >= 0; --i) {
 174       if (!aChain[i].PreHandleEventOnly()) {
 175         return &aChain[i];
 176       }
 177     }
 178     return nullptr;
 179   }
 180
 181   bool IsValid() const {
 182     NS_WARNING_ASSERTION(!!(mTarget), "Event target is not valid!");
 183     return !!(mTarget);
 184   }
 185
 186   EventTarget* GetNewTarget() const { return mNewTarget; }
 187
 188   void SetNewTarget(EventTarget* aNewTarget) { mNewTarget = aNewTarget; }
 189
 190   EventTarget* GetRetargetedRelatedTarget() { return mRetargetedRelatedTarget; }
 191
 192   void SetRetargetedRelatedTarget(EventTarget* aTarget) {
 193     mRetargetedRelatedTarget = aTarget;
 194   }
 195
 196   void SetRetargetedTouchTarget(
 197       Maybe<nsTArray<RefPtr<EventTarget>>>&& aTargets) {
 198     mRetargetedTouchTargets = std::move(aTargets);
 199   }
 200
 201   bool HasRetargetTouchTargets() const {
 202     return mRetargetedTouchTargets.isSome() || mInitialTargetTouches.isSome();
 203   }
 204
 205   void RetargetTouchTargets(WidgetTouchEvent* aTouchEvent, Event* aDOMEvent) {
 206     MOZ_ASSERT(HasRetargetTouchTargets());
 207     MOZ_ASSERT(aTouchEvent,
 208                "mRetargetedTouchTargets should be empty when dispatching "
 209                "non-touch events.");
 210
 211     if (mRetargetedTouchTargets.isSome()) {
 212       WidgetTouchEvent::TouchArray& touches = aTouchEvent->mTouches;
 213       MOZ_ASSERT(!touches.Length() ||
 214                  touches.Length() == mRetargetedTouchTargets->Length());
 215       for (uint32_t i = 0; i < touches.Length(); ++i) {
 216         touches[i]->mTarget = mRetargetedTouchTargets->ElementAt(i);
 217       }
 218     }
 219
 220     if (aDOMEvent) {
 221       // The number of touch objects in targetTouches list may change depending
 222       // on the retargeting.
 223       TouchEvent* touchDOMEvent = static_cast<TouchEvent*>(aDOMEvent);
 224       TouchList* targetTouches = touchDOMEvent->GetExistingTargetTouches();
 225       if (targetTouches) {
 226         targetTouches->Clear();
 227         if (mInitialTargetTouches.isSome()) {
 228           for (uint32_t i = 0; i < mInitialTargetTouches->Length(); ++i) {
 229             Touch* touch = mInitialTargetTouches->ElementAt(i);
 230             if (touch) {
 231               touch->mTarget = touch->mOriginalTarget;
 232             }
 233             targetTouches->Append(touch);
 234           }
 235         }
 236       }
 237     }
 238   }
 239
 240   void SetInitialTargetTouches(
 241       Maybe<nsTArray<RefPtr<dom::Touch>>>&& aInitialTargetTouches) {
 242     mInitialTargetTouches = std::move(aInitialTargetTouches);
 243   }
 244
 245   void SetForceContentDispatch(bool aForce) {
 246     mFlags.mForceContentDispatch = aForce;
 247   }
 248
 249   bool ForceContentDispatch() const { return mFlags.mForceContentDispatch; }
 250
 251   void SetWantsWillHandleEvent(bool aWants) {
 252     mFlags.mWantsWillHandleEvent = aWants;
 253   }
 254
 255   bool WantsWillHandleEvent() const { return mFlags.mWantsWillHandleEvent; }
 256
 257   void SetWantsPreHandleEvent(bool aWants) {
 258     mFlags.mWantsPreHandleEvent = aWants;
 259   }
 260
 261   bool WantsPreHandleEvent() const { return mFlags.mWantsPreHandleEvent; }
 262
 263   void SetPreHandleEventOnly(bool aWants) {
 264     mFlags.mPreHandleEventOnly = aWants;
 265   }
 266
 267   bool PreHandleEventOnly() const { return mFlags.mPreHandleEventOnly; }
 268
 269   void SetRootOfClosedTree(bool aSet) { mFlags.mRootOfClosedTree = aSet; }
 270
 271   bool IsRootOfClosedTree() const { return mFlags.mRootOfClosedTree; }
 272
 273   void SetItemInShadowTree(bool aSet) { mFlags.mItemInShadowTree = aSet; }
 274
 275   bool IsItemInShadowTree() const { return mFlags.mItemInShadowTree; }
 276
 277   void SetIsSlotInClosedTree(bool aSet) { mFlags.mIsSlotInClosedTree = aSet; }
 278
 279   bool IsSlotInClosedTree() const { return mFlags.mIsSlotInClosedTree; }
 280
 281   void SetIsChromeHandler(bool aSet) { mFlags.mIsChromeHandler = aSet; }
 282
 283   bool IsChromeHandler() const { return mFlags.mIsChromeHandler; }
 284
 285   void SetMayHaveListenerManager(bool aMayHave) {
 286     mFlags.mMayHaveManager = aMayHave;
 287   }
 288
 289   bool MayHaveListenerManager() { return mFlags.mMayHaveManager; }
 290
 291   EventTarget* CurrentTarget() const { return mTarget; }
 292
 293   /**
 294    * Dispatches event through the event target chain.
 295    * Handles capture, target and bubble phases both in default
 296    * and system event group and calls also PostHandleEvent for each
 297    * item in the chain.
 298    */
 299   MOZ_CAN_RUN_SCRIPT
 300   static void HandleEventTargetChain(nsTArray<EventTargetChainItem>& aChain,
 301                                      EventChainPostVisitor& aVisitor,
 302                                      EventDispatchingCallback* aCallback,
 303                                      ELMCreationDetector& aCd);
 304
 305   /**
 306    * Resets aVisitor object and calls GetEventTargetParent.
 307    * Copies mItemFlags and mItemData to the current EventTargetChainItem.
 308    */
 309   void GetEventTargetParent(EventChainPreVisitor& aVisitor);
 310
 311   /**
 312    * Copies mItemFlags, mItemData to aVisitor,
 313    * calls LegacyPreActivationBehavior and copies both members back
 314    * to this EventTargetChainitem.
 315    */
 316   void LegacyPreActivationBehavior(EventChainVisitor& aVisitor);
 317
 318   /**
 319    * Copies mItemFlags and mItemData to aVisitor and calls ActivationBehavior.
 320    */
 321   MOZ_CAN_RUN_SCRIPT
 322   void ActivationBehavior(EventChainPostVisitor& aVisitor);
 323
 324   /**
 325    * Copies mItemFlags and mItemData to aVisitor and
 326    * calls LegacyCanceledActivationBehavior.
 327    */
 328   void LegacyCanceledActivationBehavior(EventChainPostVisitor& aVisitor);
 329
 330   /**
 331    * Copies mItemFlags and mItemData to aVisitor.
 332    * Calls PreHandleEvent for those items which called SetWantsPreHandleEvent.
 333    */
 334   void PreHandleEvent(EventChainVisitor& aVisitor);
 335
 336   /**
 337    * If the current item in the event target chain has an event listener
 338    * manager, this method calls EventListenerManager::HandleEvent().
 339    */
 340   void HandleEvent(EventChainPostVisitor& aVisitor, ELMCreationDetector& aCd) {
 341     if (WantsWillHandleEvent()) {
 342       mTarget->WillHandleEvent(aVisitor);
 343     }
 344     if (aVisitor.mEvent->PropagationStopped()) {
 345       return;
 346     }
 347     if (aVisitor.mEvent->mFlags.mOnlySystemGroupDispatch &&
 348         !aVisitor.mEvent->mFlags.mInSystemGroup) {
 349       return;
 350     }
 351     if (aVisitor.mEvent->mFlags.mOnlySystemGroupDispatchInContent &&
 352         !aVisitor.mEvent->mFlags.mInSystemGroup && !IsCurrentTargetChrome()) {
 353       return;
 354     }
 355     if (!mManager) {
 356       if (!MayHaveListenerManager() && !aCd.MayHaveNewListenerManager()) {
 357         return;
 358       }
 359       mManager = mTarget->GetExistingListenerManager();
 360     }
 361     if (mManager) {
 362       NS_ASSERTION(aVisitor.mEvent->mCurrentTarget == nullptr,
 363                    "CurrentTarget should be null!");
 364
 365       mManager->HandleEvent(aVisitor.mPresContext, aVisitor.mEvent,
 366                             &aVisitor.mDOMEvent, CurrentTarget(),
 367                             &aVisitor.mEventStatus, IsItemInShadowTree());
 368       NS_ASSERTION(aVisitor.mEvent->mCurrentTarget == nullptr,
 369                    "CurrentTarget should be null!");
 370     }
 371   }
 372
 373   /**
 374    * Copies mItemFlags and mItemData to aVisitor and calls PostHandleEvent.
 375    */
 376   MOZ_CAN_RUN_SCRIPT void PostHandleEvent(EventChainPostVisitor& aVisitor);
 377
 378  private:
 379   const nsCOMPtr<EventTarget> mTarget;
 380   nsCOMPtr<EventTarget> mRetargetedRelatedTarget;
 381   Maybe<nsTArray<RefPtr<EventTarget>>> mRetargetedTouchTargets;
 382   Maybe<nsTArray<RefPtr<dom::Touch>>> mInitialTargetTouches;
 383
 384   class EventTargetChainFlags {
 385    public:
 386     explicit EventTargetChainFlags() { SetRawFlags(0); }
 387     // Cached flags for each EventTargetChainItem which are set when calling
 388     // GetEventTargetParent to create event target chain. They are used to
 389     // manage or speedup event dispatching.
 390     bool mForceContentDispatch : 1;
 391     bool mWantsWillHandleEvent : 1;
 392     bool mMayHaveManager : 1;
 393     bool mChechedIfChrome : 1;
 394     bool mIsChromeContent : 1;
 395     bool mWantsPreHandleEvent : 1;
 396     bool mPreHandleEventOnly : 1;
 397     bool mRootOfClosedTree : 1;
 398     bool mItemInShadowTree : 1;
 399     bool mIsSlotInClosedTree : 1;
 400     bool mIsChromeHandler : 1;
 401
 402    private:
 403     using RawFlags = uint32_t;
 404     void SetRawFlags(RawFlags aRawFlags) {
 405       static_assert(
 406           sizeof(EventTargetChainFlags) <= sizeof(RawFlags),
 407           "EventTargetChainFlags must not be bigger than the RawFlags");
 408       memcpy(this, &aRawFlags, sizeof(EventTargetChainFlags));
 409     }
 410   } mFlags;
 411
 412   uint16_t mItemFlags;
 413   nsCOMPtr<nsISupports> mItemData;
 414   // Event retargeting must happen whenever mNewTarget is non-null.
 415   nsCOMPtr<EventTarget> mNewTarget;
 416   // Cache mTarget's event listener manager.
 417   RefPtr<EventListenerManager> mManager;
 418
 419   bool IsCurrentTargetChrome() {
 420     if (!mFlags.mChechedIfChrome) {
 421       mFlags.mChechedIfChrome = true;
 422       if (IsEventTargetChrome(mTarget)) {
 423         mFlags.mIsChromeContent = true;
 424       }
 425     }
 426     return mFlags.mIsChromeContent;
 427   }
 428 };
 429
 430 void EventTargetChainItem::GetEventTargetParent(
 431     EventChainPreVisitor& aVisitor) {
 432   aVisitor.Reset();
 433   mTarget->GetEventTargetParent(aVisitor);
 434   SetForceContentDispatch(aVisitor.mForceContentDispatch);
 435   SetWantsWillHandleEvent(aVisitor.mWantsWillHandleEvent);
 436   SetMayHaveListenerManager(aVisitor.mMayHaveListenerManager);
 437   SetWantsPreHandleEvent(aVisitor.mWantsPreHandleEvent);
 438   SetPreHandleEventOnly(aVisitor.mWantsPreHandleEvent && !aVisitor.mCanHandle);
 439   SetRootOfClosedTree(aVisitor.mRootOfClosedTree);
 440   SetItemInShadowTree(aVisitor.mItemInShadowTree);
 441   SetRetargetedRelatedTarget(aVisitor.mRetargetedRelatedTarget);
 442   SetRetargetedTouchTarget(std::move(aVisitor.mRetargetedTouchTargets));
 443   mItemFlags = aVisitor.mItemFlags;
 444   mItemData = aVisitor.mItemData;
 445 }
 446
 447 void EventTargetChainItem::LegacyPreActivationBehavior(
 448     EventChainVisitor& aVisitor) {
 449   aVisitor.mItemFlags = mItemFlags;
 450   aVisitor.mItemData = mItemData;
 451   mTarget->LegacyPreActivationBehavior(aVisitor);
 452   mItemFlags = aVisitor.mItemFlags;
 453   mItemData = aVisitor.mItemData;
 454 }
 455
 456 void EventTargetChainItem::PreHandleEvent(EventChainVisitor& aVisitor) {
 457   if (!WantsPreHandleEvent()) {
 458     return;
 459   }
 460   aVisitor.mItemFlags = mItemFlags;
 461   aVisitor.mItemData = mItemData;
 462   Unused << mTarget->PreHandleEvent(aVisitor);
 463   MOZ_ASSERT(mItemFlags == aVisitor.mItemFlags);
 464   MOZ_ASSERT(mItemData == aVisitor.mItemData);
 465 }
 466
 467 void EventTargetChainItem::ActivationBehavior(EventChainPostVisitor& aVisitor) {
 468   aVisitor.mItemFlags = mItemFlags;
 469   aVisitor.mItemData = mItemData;
 470   mTarget->ActivationBehavior(aVisitor);
 471   MOZ_ASSERT(mItemFlags == aVisitor.mItemFlags);
 472   MOZ_ASSERT(mItemData == aVisitor.mItemData);
 473 }
 474
 475 void EventTargetChainItem::LegacyCanceledActivationBehavior(
 476     EventChainPostVisitor& aVisitor) {
 477   aVisitor.mItemFlags = mItemFlags;
 478   aVisitor.mItemData = mItemData;
 479   mTarget->LegacyCanceledActivationBehavior(aVisitor);
 480   MOZ_ASSERT(mItemFlags == aVisitor.mItemFlags);
 481   MOZ_ASSERT(mItemData == aVisitor.mItemData);
 482 }
 483
 484 void EventTargetChainItem::PostHandleEvent(EventChainPostVisitor& aVisitor) {
 485   aVisitor.mItemFlags = mItemFlags;
 486   aVisitor.mItemData = mItemData;
 487   mTarget->PostHandleEvent(aVisitor);
 488   MOZ_ASSERT(mItemFlags == aVisitor.mItemFlags);
 489   MOZ_ASSERT(mItemData == aVisitor.mItemData);
 490 }
 491
 492 void EventTargetChainItem::HandleEventTargetChain(
 493     nsTArray<EventTargetChainItem>& aChain, EventChainPostVisitor& aVisitor,
 494     EventDispatchingCallback* aCallback, ELMCreationDetector& aCd) {
 495   // Save the target so that it can be restored later.
 496   nsCOMPtr<EventTarget> firstTarget = aVisitor.mEvent->mTarget;
 497   nsCOMPtr<EventTarget> firstRelatedTarget = aVisitor.mEvent->mRelatedTarget;
 498   Maybe<AutoTArray<nsCOMPtr<EventTarget>, 10>> firstTouchTargets;
 499   WidgetTouchEvent* touchEvent = nullptr;
 500   if (aVisitor.mEvent->mClass == eTouchEventClass) {
 501     touchEvent = aVisitor.mEvent->AsTouchEvent();
 502     if (!aVisitor.mEvent->mFlags.mInSystemGroup) {
 503       firstTouchTargets.emplace();
 504       WidgetTouchEvent* touchEvent = aVisitor.mEvent->AsTouchEvent();
 505       WidgetTouchEvent::TouchArray& touches = touchEvent->mTouches;
 506       for (uint32_t i = 0; i < touches.Length(); ++i) {
 507         firstTouchTargets->AppendElement(touches[i]->mTarget);
 508       }
 509     }
 510   }
 511
 512   uint32_t chainLength = aChain.Length();
 513   EventTargetChainItem* chain = aChain.Elements();
 514   uint32_t firstCanHandleEventTargetIdx =
 515       EventTargetChainItem::GetFirstCanHandleEventTargetIdx(aChain);
 516
 517   // Capture
 518   aVisitor.mEvent->mFlags.mInCapturePhase = true;
 519   aVisitor.mEvent->mFlags.mInBubblingPhase = false;
 520   aVisitor.mEvent->mFlags.mInTargetPhase = false;
 521   for (uint32_t i = chainLength - 1; i > firstCanHandleEventTargetIdx; --i) {
 522     EventTargetChainItem& item = chain[i];
 523     if (item.PreHandleEventOnly()) {
 524       continue;
 525     }
 526     if ((!aVisitor.mEvent->mFlags.mNoContentDispatch ||
 527          item.ForceContentDispatch()) &&
 528         !aVisitor.mEvent->PropagationStopped()) {
 529       item.HandleEvent(aVisitor, aCd);
 530     }
 531
 532     if (item.GetNewTarget()) {
 533       // item is at anonymous boundary. Need to retarget for the child items.
 534       for (uint32_t j = i; j > 0; --j) {
 535         uint32_t childIndex = j - 1;
 536         EventTarget* newTarget = chain[childIndex].GetNewTarget();
 537         if (newTarget) {
 538           aVisitor.mEvent->mTarget = newTarget;
 539           break;
 540         }
 541       }
 542     }
 543
 544     // https://dom.spec.whatwg.org/#dispatching-events
 545     // Step 14.2
 546     // "Set event's relatedTarget to tuple's relatedTarget."
 547     // Note, the initial retargeting was done already when creating
 548     // event target chain, so we need to do this only after calling
 549     // HandleEvent, not before, like in the specification.
 550     if (item.GetRetargetedRelatedTarget()) {
 551       bool found = false;
 552       for (uint32_t j = i; j > 0; --j) {
 553         uint32_t childIndex = j - 1;
 554         EventTarget* relatedTarget =
 555             chain[childIndex].GetRetargetedRelatedTarget();
 556         if (relatedTarget) {
 557           found = true;
 558           aVisitor.mEvent->mRelatedTarget = relatedTarget;
 559           break;
 560         }
 561       }
 562       if (!found) {
 563         aVisitor.mEvent->mRelatedTarget =
 564             aVisitor.mEvent->mOriginalRelatedTarget;
 565       }
 566     }
 567
 568     if (item.HasRetargetTouchTargets()) {
 569       bool found = false;
 570       for (uint32_t j = i; j > 0; --j) {
 571         uint32_t childIndex = j - 1;
 572         if (chain[childIndex].HasRetargetTouchTargets()) {
 573           found = true;
 574           chain[childIndex].RetargetTouchTargets(touchEvent,
 575                                                  aVisitor.mDOMEvent);
 576           break;
 577         }
 578       }
 579       if (!found) {
 580         WidgetTouchEvent::TouchArray& touches = touchEvent->mTouches;
 581         for (uint32_t i = 0; i < touches.Length(); ++i) {
 582           touches[i]->mTarget = touches[i]->mOriginalTarget;
 583         }
 584       }
 585     }
 586   }
 587
 588   // Target
 589   aVisitor.mEvent->mFlags.mInTargetPhase = true;
 590   EventTargetChainItem& targetItem = chain[firstCanHandleEventTargetIdx];
 591   // Need to explicitly retarget touch targets so that initial targets get set
 592   // properly in case nothing else retargeted touches.
 593   if (targetItem.HasRetargetTouchTargets()) {
 594     targetItem.RetargetTouchTargets(touchEvent, aVisitor.mDOMEvent);
 595   }
 596   if (!aVisitor.mEvent->PropagationStopped() &&
 597       (!aVisitor.mEvent->mFlags.mNoContentDispatch ||
 598        targetItem.ForceContentDispatch())) {
 599     targetItem.HandleEvent(aVisitor, aCd);
 600   }
 601   aVisitor.mEvent->mFlags.mInCapturePhase = false;
 602   aVisitor.mEvent->mFlags.mInBubblingPhase = true;
 603   if (!aVisitor.mEvent->PropagationStopped() &&
 604       (!aVisitor.mEvent->mFlags.mNoContentDispatch ||
 605        targetItem.ForceContentDispatch())) {
 606     targetItem.HandleEvent(aVisitor, aCd);
 607   }
 608
 609   if (aVisitor.mEvent->mFlags.mInSystemGroup) {
 610     targetItem.PostHandleEvent(aVisitor);
 611   }
 612   aVisitor.mEvent->mFlags.mInTargetPhase = false;
 613
 614   // Bubble
 615   for (uint32_t i = firstCanHandleEventTargetIdx + 1; i < chainLength; ++i) {
 616     EventTargetChainItem& item = chain[i];
 617     if (item.PreHandleEventOnly()) {
 618       continue;
 619     }
 620     EventTarget* newTarget = item.GetNewTarget();
 621     if (newTarget) {
 622       // Item is at anonymous boundary. Need to retarget for the current item
 623       // and for parent items.
 624       aVisitor.mEvent->mTarget = newTarget;
 625     }
 626
 627     // https://dom.spec.whatwg.org/#dispatching-events
 628     // Step 15.2
 629     // "Set event's relatedTarget to tuple's relatedTarget."
 630     EventTarget* relatedTarget = item.GetRetargetedRelatedTarget();
 631     if (relatedTarget) {
 632       aVisitor.mEvent->mRelatedTarget = relatedTarget;
 633     }
 634
 635     if (item.HasRetargetTouchTargets()) {
 636       item.RetargetTouchTargets(touchEvent, aVisitor.mDOMEvent);
 637     }
 638
 639     if (aVisitor.mEvent->mFlags.mBubbles || newTarget) {
 640       if ((!aVisitor.mEvent->mFlags.mNoContentDispatch ||
 641            item.ForceContentDispatch()) &&
 642           !aVisitor.mEvent->PropagationStopped()) {
 643         item.HandleEvent(aVisitor, aCd);
 644       }
 645       if (aVisitor.mEvent->mFlags.mInSystemGroup) {
 646         item.PostHandleEvent(aVisitor);
 647       }
 648     }
 649   }
 650   aVisitor.mEvent->mFlags.mInBubblingPhase = false;
 651
 652   if (!aVisitor.mEvent->mFlags.mInSystemGroup &&
 653       aVisitor.mEvent->IsAllowedToDispatchInSystemGroup()) {
 654     // Dispatch to the system event group.  Make sure to clear the
 655     // STOP_DISPATCH flag since this resets for each event group.
 656     aVisitor.mEvent->mFlags.mPropagationStopped = false;
 657     aVisitor.mEvent->mFlags.mImmediatePropagationStopped = false;
 658
 659     // Setting back the original target of the event.
 660     aVisitor.mEvent->mTarget = aVisitor.mEvent->mOriginalTarget;
 661     aVisitor.mEvent->mRelatedTarget = aVisitor.mEvent->mOriginalRelatedTarget;
 662     if (firstTouchTargets) {
 663       WidgetTouchEvent::TouchArray& touches = touchEvent->mTouches;
 664       for (uint32_t i = 0; i < touches.Length(); ++i) {
 665         touches[i]->mTarget = touches[i]->mOriginalTarget;
 666       }
 667     }
 668
 669     // Special handling if PresShell (or some other caller)
 670     // used a callback object.
 671     if (aCallback) {
 672       aCallback->HandleEvent(aVisitor);
 673     }
 674
 675     // Retarget for system event group (which does the default handling too).
 676     // Setting back the target which was used also for default event group.
 677     aVisitor.mEvent->mTarget = firstTarget;
 678     aVisitor.mEvent->mRelatedTarget = firstRelatedTarget;
 679     if (firstTouchTargets) {
 680       WidgetTouchEvent::TouchArray& touches = touchEvent->mTouches;
 681       for (uint32_t i = 0; i < firstTouchTargets->Length(); ++i) {
 682         touches[i]->mTarget = firstTouchTargets->ElementAt(i);
 683       }
 684     }
 685
 686     aVisitor.mEvent->mFlags.mInSystemGroup = true;
 687     HandleEventTargetChain(aChain, aVisitor, aCallback, aCd);
 688     aVisitor.mEvent->mFlags.mInSystemGroup = false;
 689
 690     // After dispatch, clear all the propagation flags so that
 691     // system group listeners don't affect to the event.
 692     aVisitor.mEvent->mFlags.mPropagationStopped = false;
 693     aVisitor.mEvent->mFlags.mImmediatePropagationStopped = false;
 694   }
 695 }
 696
 697 // There are often 2 nested event dispatches ongoing at the same time, so
 698 // have 2 separate caches.
 699 static const uint32_t kCachedMainThreadChainSize = 128;
 700 struct CachedChains {
 701   nsTArray<EventTargetChainItem> mChain1;
 702   nsTArray<EventTargetChainItem> mChain2;
 703 };
 704 static CachedChains* sCachedMainThreadChains = nullptr;
 705
 706 /* static */
 707 void EventDispatcher::Shutdown() {
 708   delete sCachedMainThreadChains;
 709   sCachedMainThreadChains = nullptr;
 710 }
 711
 712 EventTargetChainItem* EventTargetChainItemForChromeTarget(
 713     nsTArray<EventTargetChainItem>& aChain, nsINode* aNode,
 714     EventTargetChainItem* aChild = nullptr) {
 715   if (!aNode->IsInComposedDoc()) {
 716     return nullptr;
 717   }
 718   nsPIDOMWindowInner* win = aNode->OwnerDoc()->GetInnerWindow();
 719   EventTarget* piTarget = win ? win->GetParentTarget() : nullptr;
 720   NS_ENSURE_TRUE(piTarget, nullptr);
 721
 722   EventTargetChainItem* etci = EventTargetChainItem::Create(
 723       aChain, piTarget->GetTargetForEventTargetChain(), aChild);
 724   if (!etci->IsValid()) {
 725     EventTargetChainItem::DestroyLast(aChain, etci);
 726     return nullptr;
 727   }
 728   return etci;
 729 }
 730
 731 /* static */ EventTargetChainItem* MayRetargetToChromeIfCanNotHandleEvent(
 732     nsTArray<EventTargetChainItem>& aChain, EventChainPreVisitor& aPreVisitor,
 733     EventTargetChainItem* aTargetEtci, EventTargetChainItem* aChildEtci,
 734     nsINode* aContent) {
 735   if (!aPreVisitor.mWantsPreHandleEvent) {
 736     // Keep EventTargetChainItem if we need to call PreHandleEvent on it.
 737     EventTargetChainItem::DestroyLast(aChain, aTargetEtci);
 738   }
 739   if (aPreVisitor.mAutomaticChromeDispatch && aContent) {
 740     aPreVisitor.mRelatedTargetRetargetedInCurrentScope = false;
 741     // Event target couldn't handle the event. Try to propagate to chrome.
 742     EventTargetChainItem* chromeTargetEtci =
 743         EventTargetChainItemForChromeTarget(aChain, aContent, aChildEtci);
 744     if (chromeTargetEtci) {
 745       // If we propagate to chrome, need to ensure we mark
 746       // EventTargetChainItem to be chrome handler so that event.composedPath()
 747       // can return the right value.
 748       chromeTargetEtci->SetIsChromeHandler(true);
 749       chromeTargetEtci->GetEventTargetParent(aPreVisitor);
 750       return chromeTargetEtci;
 751     }
 752   }
 753   return nullptr;
 754 }
 755
 756 static bool ShouldClearTargets(WidgetEvent* aEvent) {
 757   if (nsIContent* finalTarget =
 758           nsIContent::FromEventTargetOrNull(aEvent->mTarget)) {
 759     if (finalTarget->SubtreeRoot()->IsShadowRoot()) {
 760       return true;
 761     }
 762   }
 763
 764   if (nsIContent* finalRelatedTarget =
 765           nsIContent::FromEventTargetOrNull(aEvent->mRelatedTarget)) {
 766     if (finalRelatedTarget->SubtreeRoot()->IsShadowRoot()) {
 767       return true;
 768     }
 769   }
 770   // XXXsmaug Check also all the touch objects.
 771
 772   return false;
 773 }
 774
 775 static void DescribeEventTargetForProfilerMarker(const EventTarget* aTarget,
 776                                                  nsACString& aDescription) {
 777   auto* node = aTarget->GetAsNode();
 778   if (node) {
 779     if (node->IsElement()) {
 780       nsAutoString nodeDescription;
 781       node->AsElement()->Describe(nodeDescription, true);
 782       aDescription = NS_ConvertUTF16toUTF8(nodeDescription);
 783     } else if (node->IsDocument()) {
 784       aDescription.AssignLiteral("document");
 785     } else if (node->IsText()) {
 786       aDescription.AssignLiteral("text");
 787     } else if (node->IsDocumentFragment()) {
 788       aDescription.AssignLiteral("document fragment");
 789     }
 790   } else if (aTarget->IsInnerWindow() || aTarget->IsOuterWindow()) {
 791     aDescription.AssignLiteral("window");
 792   } else if (aTarget->IsRootWindow()) {
 793     aDescription.AssignLiteral("root window");
 794   } else {
 795     // Probably something that inherits from DOMEventTargetHelper.
 796   }
 797 }
 798
 799 /* static */
 800 nsresult EventDispatcher::Dispatch(EventTarget* aTarget,
 801                                    nsPresContext* aPresContext,
 802                                    WidgetEvent* aEvent, Event* aDOMEvent,
 803                                    nsEventStatus* aEventStatus,
 804                                    EventDispatchingCallback* aCallback,
 805                                    nsTArray<EventTarget*>* aTargets) {
 806   AUTO_PROFILER_LABEL_HOT("EventDispatcher::Dispatch", OTHER);
 807
 808   NS_ASSERTION(aEvent, "Trying to dispatch without WidgetEvent!");
 809   NS_ENSURE_TRUE(!aEvent->mFlags.mIsBeingDispatched,
 810                  NS_ERROR_DOM_INVALID_STATE_ERR);
 811   NS_ASSERTION(!aTargets || !aEvent->mMessage, "Wrong parameters!");
 812
 813   // If we're dispatching an already created DOMEvent object, make
 814   // sure it is initialized!
 815   // If aTargets is non-null, the event isn't going to be dispatched.
 816   NS_ENSURE_TRUE(aEvent->mMessage || !aDOMEvent || aTargets,
 817                  NS_ERROR_DOM_INVALID_STATE_ERR);
 818
 819   // Events shall not be fired while we are in stable state to prevent anything
 820   // visible from the scripts.
 821   MOZ_ASSERT(!nsContentUtils::IsInStableOrMetaStableState());
 822   NS_ENSURE_TRUE(!nsContentUtils::IsInStableOrMetaStableState(),
 823                  NS_ERROR_DOM_INVALID_STATE_ERR);
 824
 825   nsCOMPtr<EventTarget> target(aTarget);
 826
 827   RefPtr<PerformanceEventTiming> eventTimingEntry;
 828   // Similar to PerformancePaintTiming, we don't need to
 829   // expose them for printing documents
 830   if (aPresContext && !aPresContext->IsPrintingOrPrintPreview()) {
 831     eventTimingEntry =
 832         PerformanceEventTiming::TryGenerateEventTiming(target, aEvent);
 833
 834     if (aEvent->IsTrusted() && aEvent->mMessage == eScroll) {
 835       if (auto* perf = aPresContext->GetPerformanceMainThread()) {
 836         if (!perf->HasDispatchedScrollEvent()) {
 837           perf->SetHasDispatchedScrollEvent();
 838         }
 839       }
 840     }
 841   }
 842
 843   bool retargeted = false;
 844
 845   if (aEvent->mFlags.mRetargetToNonNativeAnonymous) {
 846     nsIContent* content = nsIContent::FromEventTargetOrNull(target);
 847     if (content && content->IsInNativeAnonymousSubtree()) {
 848       nsCOMPtr<EventTarget> newTarget =
 849           content->FindFirstNonChromeOnlyAccessContent();
 850       NS_ENSURE_STATE(newTarget);
 851
 852       aEvent->mOriginalTarget = target;
 853       target = newTarget;
 854       retargeted = true;
 855     }
 856   }
 857
 858   if (aEvent->mFlags.mOnlyChromeDispatch) {
 859     nsCOMPtr<Document> doc;
 860     if (!IsEventTargetChrome(target, getter_AddRefs(doc)) && doc) {
 861       nsPIDOMWindowInner* win = doc->GetInnerWindow();
 862       // If we can't dispatch the event to chrome, do nothing.
 863       EventTarget* piTarget = win ? win->GetParentTarget() : nullptr;
 864       if (!piTarget) {
 865         return NS_OK;
 866       }
 867
 868       // Set the target to be the original dispatch target,
 869       aEvent->mTarget = target;
 870       // but use chrome event handler or BrowserChildMessageManager for event
 871       // target chain.
 872       target = piTarget;
 873     } else if (NS_WARN_IF(!doc)) {
 874       return NS_ERROR_UNEXPECTED;
 875     }
 876   }
 877
 878 #ifdef DEBUG
 879   if (NS_IsMainThread() && aEvent->mMessage != eVoidEvent &&
 880       !nsContentUtils::IsSafeToRunScript()) {
 881     static const auto warn = [](bool aIsSystem) {
 882       if (aIsSystem) {
 883         NS_WARNING("Fix the caller!");
 884       } else {
 885         MOZ_CRASH("This is unsafe! Fix the caller!");
 886       }
 887     };
 888     if (nsINode* node = nsINode::FromEventTargetOrNull(target)) {
 889       // If this is a node, it's possible that this is some sort of DOM tree
 890       // that is never accessed by script (for example an SVG image or XBL
 891       // binding document or whatnot).  We really only want to warn/assert here
 892       // if there might be actual scripted listeners for this event, so restrict
 893       // the warnings/asserts to the case when script can or once could touch
 894       // this node's document.
 895       Document* doc = node->OwnerDoc();
 896       bool hasHadScriptHandlingObject;
 897       nsIGlobalObject* global =
 898           doc->GetScriptHandlingObject(hasHadScriptHandlingObject);
 899       if (global || hasHadScriptHandlingObject) {
 900         warn(nsContentUtils::IsChromeDoc(doc));
 901       }
 902     } else if (nsCOMPtr<nsIGlobalObject> global = target->GetOwnerGlobal()) {
 903       warn(global->PrincipalOrNull()->IsSystemPrincipal());
 904     }
 905   }
 906
 907   if (aDOMEvent) {
 908     WidgetEvent* innerEvent = aDOMEvent->WidgetEventPtr();
 909     NS_ASSERTION(innerEvent == aEvent,
 910                  "The inner event of aDOMEvent is not the same as aEvent!");
 911   }
 912 #endif
 913
 914   nsresult rv = NS_OK;
 915   bool externalDOMEvent = !!(aDOMEvent);
 916
 917   // If we have a PresContext, make sure it doesn't die before
 918   // event dispatching is finished.
 919   RefPtr<nsPresContext> kungFuDeathGrip(aPresContext);
 920
 921   ELMCreationDetector cd;
 922   nsTArray<EventTargetChainItem> chain;
 923   if (cd.IsMainThread()) {
 924     if (!sCachedMainThreadChains) {
 925       sCachedMainThreadChains = new CachedChains();
 926     }
 927
 928     if (sCachedMainThreadChains->mChain1.Capacity() ==
 929         kCachedMainThreadChainSize) {
 930       chain = std::move(sCachedMainThreadChains->mChain1);
 931     } else if (sCachedMainThreadChains->mChain2.Capacity() ==
 932                kCachedMainThreadChainSize) {
 933       chain = std::move(sCachedMainThreadChains->mChain2);
 934     } else {
 935       chain.SetCapacity(kCachedMainThreadChainSize);
 936     }
 937   }
 938
 939   // Create the event target chain item for the event target.
 940   EventTargetChainItem* targetEtci = EventTargetChainItem::Create(
 941       chain, target->GetTargetForEventTargetChain());
 942   MOZ_ASSERT(&chain[0] == targetEtci);
 943   if (!targetEtci->IsValid()) {
 944     EventTargetChainItem::DestroyLast(chain, targetEtci);
 945     return NS_ERROR_FAILURE;
 946   }
 947
 948   // Make sure that Event::target and Event::originalTarget
 949   // point to the last item in the chain.
 950   if (!aEvent->mTarget) {
 951     // Note, CurrentTarget() points always to the object returned by
 952     // GetTargetForEventTargetChain().
 953     aEvent->mTarget = targetEtci->CurrentTarget();
 954   } else {
 955     // XXX But if the target is already set, use that. This is a hack
 956     //     for the 'load', 'beforeunload' and 'unload' events,
 957     //     which are dispatched to |window| but have document as their target.
 958     //
 959     // Make sure that the event target points to the right object.
 960     aEvent->mTarget = aEvent->mTarget->GetTargetForEventTargetChain();
 961     NS_ENSURE_STATE(aEvent->mTarget);
 962   }
 963
 964   if (retargeted) {
 965     aEvent->mOriginalTarget =
 966         aEvent->mOriginalTarget->GetTargetForEventTargetChain();
 967     NS_ENSURE_STATE(aEvent->mOriginalTarget);
 968   } else {
 969     aEvent->mOriginalTarget = aEvent->mTarget;
 970   }
 971
 972   aEvent->mOriginalRelatedTarget = aEvent->mRelatedTarget;
 973
 974   bool clearTargets = false;
 975
 976   nsCOMPtr<nsIContent> content =
 977       nsIContent::FromEventTargetOrNull(aEvent->mOriginalTarget);
 978   bool isInAnon = content && content->IsInNativeAnonymousSubtree();
 979
 980   aEvent->mFlags.mIsBeingDispatched = true;
 981
 982   Maybe<uint32_t> activationTargetItemIndex;
 983
 984   // Create visitor object and start event dispatching.
 985   // GetEventTargetParent for the original target.
 986   nsEventStatus status = aDOMEvent && aDOMEvent->DefaultPrevented()
 987                              ? nsEventStatus_eConsumeNoDefault
 988                          : aEventStatus ? *aEventStatus
 989                                         : nsEventStatus_eIgnore;
 990   nsCOMPtr<EventTarget> targetForPreVisitor = aEvent->mTarget;
 991   EventChainPreVisitor preVisitor(aPresContext, aEvent, aDOMEvent, status,
 992                                   isInAnon, targetForPreVisitor);
 993   targetEtci->GetEventTargetParent(preVisitor);
 994
 995   if (preVisitor.mWantsActivationBehavior) {
 996     MOZ_ASSERT(&chain[0] == targetEtci);
 997     activationTargetItemIndex.emplace(0);
 998   }
 999
1000   if (!preVisitor.mCanHandle) {
1001     targetEtci = MayRetargetToChromeIfCanNotHandleEvent(
1002         chain, preVisitor, targetEtci, nullptr, content);
1003   }
1004   if (!preVisitor.mCanHandle) {
1005     // The original target and chrome target (mAutomaticChromeDispatch=true)
1006     // can not handle the event but we still have to call their PreHandleEvent.
1007     for (uint32_t i = 0; i < chain.Length(); ++i) {
1008       chain[i].PreHandleEvent(preVisitor);
1009     }
1010
1011     clearTargets = ShouldClearTargets(aEvent);
1012   } else {
1013     // At least the original target can handle the event.
1014     // Setting the retarget to the |target| simplifies retargeting code.
1015     nsCOMPtr<EventTarget> t = aEvent->mTarget;
1016     targetEtci->SetNewTarget(t);
1017     // In order to not change the targetTouches array passed to TouchEvents
1018     // when dispatching events from JS, we need to store the initial Touch
1019     // objects on the list.
1020     if (aEvent->mClass == eTouchEventClass && aDOMEvent) {
1021       TouchEvent* touchEvent = static_cast<TouchEvent*>(aDOMEvent);
1022       TouchList* targetTouches = touchEvent->GetExistingTargetTouches();
1023       if (targetTouches) {
1024         Maybe<nsTArray<RefPtr<dom::Touch>>> initialTargetTouches;
1025         initialTargetTouches.emplace();
1026         for (uint32_t i = 0; i < targetTouches->Length(); ++i) {
1027           initialTargetTouches->AppendElement(targetTouches->Item(i));
1028         }
1029         targetEtci->SetInitialTargetTouches(std::move(initialTargetTouches));
1030         targetTouches->Clear();
1031       }
1032     }
1033     EventTargetChainItem* topEtci = targetEtci;
1034     targetEtci = nullptr;
1035     while (preVisitor.GetParentTarget()) {
1036       EventTarget* parentTarget = preVisitor.GetParentTarget();
1037       EventTargetChainItem* parentEtci =
1038           EventTargetChainItem::Create(chain, parentTarget, topEtci);
1039       if (!parentEtci->IsValid()) {
1040         EventTargetChainItem::DestroyLast(chain, parentEtci);
1041         rv = NS_ERROR_FAILURE;
1042         break;
1043       }
1044
1045       parentEtci->SetIsSlotInClosedTree(preVisitor.mParentIsSlotInClosedTree);
1046       parentEtci->SetIsChromeHandler(preVisitor.mParentIsChromeHandler);
1047
1048       // Item needs event retargetting.
1049       if (preVisitor.mEventTargetAtParent) {
1050         // Need to set the target of the event
1051         // so that also the next retargeting works.
1052         preVisitor.mTargetInKnownToBeHandledScope = preVisitor.mEvent->mTarget;
1053         preVisitor.mEvent->mTarget = preVisitor.mEventTargetAtParent;
1054         parentEtci->SetNewTarget(preVisitor.mEventTargetAtParent);
1055       }
1056
1057       if (preVisitor.mRetargetedRelatedTarget) {
1058         preVisitor.mEvent->mRelatedTarget = preVisitor.mRetargetedRelatedTarget;
1059       }
1060
1061       parentEtci->GetEventTargetParent(preVisitor);
1062
1063       if (preVisitor.mWantsActivationBehavior &&
1064           activationTargetItemIndex.isNothing() && aEvent->mFlags.mBubbles) {
1065         MOZ_ASSERT(&chain.LastElement() == parentEtci);
1066         activationTargetItemIndex.emplace(chain.Length() - 1);
1067       }
1068
1069       if (preVisitor.mCanHandle) {
1070         preVisitor.mTargetInKnownToBeHandledScope = preVisitor.mEvent->mTarget;
1071         topEtci = parentEtci;
1072       } else {
1073         bool ignoreBecauseOfShadowDOM = preVisitor.mIgnoreBecauseOfShadowDOM;
1074         nsCOMPtr<nsINode> disabledTarget =
1075             nsINode::FromEventTargetOrNull(parentTarget);
1076         parentEtci = MayRetargetToChromeIfCanNotHandleEvent(
1077             chain, preVisitor, parentEtci, topEtci, disabledTarget);
1078         if (parentEtci && preVisitor.mCanHandle) {
1079           preVisitor.mTargetInKnownToBeHandledScope =
1080               preVisitor.mEvent->mTarget;
1081           EventTargetChainItem* item =
1082               EventTargetChainItem::GetFirstCanHandleEventTarget(chain);
1083           if (!ignoreBecauseOfShadowDOM) {
1084             // If we ignored the target because of Shadow DOM retargeting, we
1085             // shouldn't treat the target to be in the event path at all.
1086             item->SetNewTarget(parentTarget);
1087           }
1088           topEtci = parentEtci;
1089           continue;
1090         }
1091         break;
1092       }
1093     }
1094
1095     if (activationTargetItemIndex) {
1096       chain[activationTargetItemIndex.value()].LegacyPreActivationBehavior(
1097           preVisitor);
1098     }
1099
1100     if (NS_SUCCEEDED(rv)) {
1101       if (aTargets) {
1102         aTargets->Clear();
1103         uint32_t numTargets = chain.Length();
1104         EventTarget** targets = aTargets->AppendElements(numTargets);
1105         for (uint32_t i = 0; i < numTargets; ++i) {
1106           targets[i] = chain[i].CurrentTarget()->GetTargetForDOMEvent();
1107         }
1108       } else {
1109         // Event target chain is created. PreHandle the chain.
1110         for (uint32_t i = 0; i < chain.Length(); ++i) {
1111           chain[i].PreHandleEvent(preVisitor);
1112         }
1113
1114         RefPtr<nsRefreshDriver> refreshDriver;
1115         if (aEvent->IsTrusted() &&
1116             (aEvent->mMessage == eKeyPress ||
1117              aEvent->mMessage == eMouseClick) &&
1118             aPresContext && aPresContext->GetRootPresContext()) {
1119           refreshDriver = aPresContext->GetRootPresContext()->RefreshDriver();
1120           if (refreshDriver) {
1121             refreshDriver->EnterUserInputProcessing();
1122           }
1123         }
1124         auto cleanup = MakeScopeExit([&] {
1125           if (refreshDriver) {
1126             refreshDriver->ExitUserInputProcessing();
1127           }
1128         });
1129
1130         clearTargets = ShouldClearTargets(aEvent);
1131
1132         // Handle the chain.
1133         EventChainPostVisitor postVisitor(preVisitor);
1134         MOZ_RELEASE_ASSERT(!aEvent->mPath);
1135         aEvent->mPath = &chain;
1136
1137         if (profiler_is_active()) {
1138           // Add a profiler label and a profiler marker for the actual
1139           // dispatch of the event.
1140           // This is a very hot code path, so we need to make sure not to
1141           // do this extra work when we're not profiling.
1142           if (!postVisitor.mDOMEvent) {
1143             // This is tiny bit slow, but happens only once per event.
1144             // Similar code also in EventListenerManager.
1145             RefPtr<Event> event = EventDispatcher::CreateEvent(
1146                 aEvent->mOriginalTarget, aPresContext, aEvent, u""_ns);
1147             event.swap(postVisitor.mDOMEvent);
1148           }
1149           nsAutoString typeStr;
1150           postVisitor.mDOMEvent->GetType(typeStr);
1151           AUTO_PROFILER_LABEL_DYNAMIC_LOSSY_NSSTRING(
1152               "EventDispatcher::Dispatch", OTHER, typeStr);
1153
1154           MarkerInnerWindowId innerWindowId;
1155           if (nsIGlobalObject* global = aEvent->mTarget->GetOwnerGlobal()) {
1156             if (nsPIDOMWindowInner* inner = global->GetAsInnerWindow()) {
1157               innerWindowId = MarkerInnerWindowId{inner->WindowID()};
1158             }
1159           }
1160
1161           struct DOMEventMarker {
1162             static constexpr Span<const char> MarkerTypeName() {
1163               return MakeStringSpan("DOMEvent");
1164             }
1165             static void StreamJSONMarkerData(
1166                 baseprofiler::SpliceableJSONWriter& aWriter,
1167                 const ProfilerString16View& aEventType,
1168                 const nsCString& aTarget, const TimeStamp& aStartTime,
1169                 const TimeStamp& aEventTimeStamp) {
1170               aWriter.StringProperty("eventType",
1171                                      NS_ConvertUTF16toUTF8(aEventType));
1172               if (!aTarget.IsEmpty()) {
1173                 aWriter.StringProperty("target", aTarget);
1174               }
1175               // This is the event processing latency, which is the time from
1176               // when the event was created, to when it was started to be
1177               // processed. Note that the computation of this latency is
1178               // deferred until serialization time, at the expense of some extra
1179               // memory.
1180               aWriter.DoubleProperty(
1181                   "latency", (aStartTime - aEventTimeStamp).ToMilliseconds());
1182             }
1183             static MarkerSchema MarkerTypeDisplay() {
1184               using MS = MarkerSchema;
1185               MS schema{MS::Location::MarkerChart, MS::Location::MarkerTable,
1186                         MS::Location::TimelineOverview};
1187               schema.SetChartLabel("{marker.data.eventType}");
1188               schema.SetTooltipLabel("{marker.data.eventType} - DOMEvent");
1189               schema.SetTableLabel(
1190                   "{marker.data.eventType} - {marker.data.target}");
1191               schema.AddKeyLabelFormatSearchable("target", "Event Target",
1192                                                  MS::Format::String,
1193                                                  MS::Searchable::Searchable);
1194               schema.AddKeyLabelFormat("latency", "Latency",
1195                                        MS::Format::Duration);
1196               schema.AddKeyLabelFormatSearchable("eventType", "Event Type",
1197                                                  MS::Format::String,
1198                                                  MS::Searchable::Searchable);
1199               return schema;
1200             }
1201           };
1202
1203           nsAutoCString target;
1204           DescribeEventTargetForProfilerMarker(aEvent->mTarget, target);
1205
1206           auto startTime = TimeStamp::Now();
1207           profiler_add_marker("DOMEvent", geckoprofiler::category::DOM,
1208                               {MarkerTiming::IntervalStart(startTime),
1209                                MarkerInnerWindowId(innerWindowId)},
1210                               DOMEventMarker{}, typeStr, target, startTime,
1211                               aEvent->mTimeStamp);
1212
1213           EventTargetChainItem::HandleEventTargetChain(chain, postVisitor,
1214                                                        aCallback, cd);
1215
1216           profiler_add_marker(
1217               "DOMEvent", geckoprofiler::category::DOM,
1218               {MarkerTiming::IntervalEnd(), std::move(innerWindowId)},
1219               DOMEventMarker{}, typeStr, target, startTime, aEvent->mTimeStamp);
1220         } else {
1221           EventTargetChainItem::HandleEventTargetChain(chain, postVisitor,
1222                                                        aCallback, cd);
1223         }
1224         aEvent->mPath = nullptr;
1225
1226         if (aEvent->IsTrusted() &&
1227             (aEvent->mMessage == eKeyPress ||
1228              aEvent->mMessage == eMouseClick) &&
1229             aPresContext && aPresContext->GetRootPresContext()) {
1230           nsRefreshDriver* driver =
1231               aPresContext->GetRootPresContext()->RefreshDriver();
1232           if (driver && driver->HasPendingTick()) {
1233             switch (aEvent->mMessage) {
1234               case eKeyPress:
1235                 driver->RegisterCompositionPayload(
1236                     {layers::CompositionPayloadType::eKeyPress,
1237                      aEvent->mTimeStamp});
1238                 break;
1239               case eMouseClick: {
1240                 if (aEvent->AsMouseEvent()->mInputSource ==
1241                         MouseEvent_Binding::MOZ_SOURCE_MOUSE ||
1242                     aEvent->AsMouseEvent()->mInputSource ==
1243                         MouseEvent_Binding::MOZ_SOURCE_TOUCH) {
1244                   driver->RegisterCompositionPayload(
1245                       {layers::CompositionPayloadType::eMouseUpFollowedByClick,
1246                        aEvent->mTimeStamp});
1247                 }
1248                 break;
1249               }
1250               default:
1251                 break;
1252             }
1253           }
1254         }
1255
1256         preVisitor.mEventStatus = postVisitor.mEventStatus;
1257         // If the DOM event was created during event flow.
1258         if (!preVisitor.mDOMEvent && postVisitor.mDOMEvent) {
1259           preVisitor.mDOMEvent = postVisitor.mDOMEvent;
1260         }
1261       }
1262     }
1263   }
1264
1265   // Note, EventTargetChainItem objects are deleted when the chain goes out of
1266   // the scope.
1267
1268   aEvent->mFlags.mIsBeingDispatched = false;
1269   aEvent->mFlags.mDispatchedAtLeastOnce = true;
1270
1271   if (eventTimingEntry) {
1272     eventTimingEntry->FinalizeEventTiming(aEvent->mTarget);
1273   }
1274   // https://dom.spec.whatwg.org/#concept-event-dispatch
1275   // step 10. If clearTargets, then:
1276   //          1. Set event's target to null.
1277   //          2. Set event's relatedTarget to null.
1278   //          3. Set event's touch target list to the empty list.
1279   if (clearTargets) {
1280     aEvent->mTarget = nullptr;
1281     aEvent->mOriginalTarget = nullptr;
1282     aEvent->mRelatedTarget = nullptr;
1283     aEvent->mOriginalRelatedTarget = nullptr;
1284     // XXXsmaug Check also all the touch objects.
1285   }
1286
1287   if (activationTargetItemIndex) {
1288     EventChainPostVisitor postVisitor(preVisitor);
1289     if (preVisitor.mEventStatus == nsEventStatus_eConsumeNoDefault) {
1290       chain[activationTargetItemIndex.value()].LegacyCanceledActivationBehavior(
1291           postVisitor);
1292     } else {
1293       chain[activationTargetItemIndex.value()].ActivationBehavior(postVisitor);
1294     }
1295     preVisitor.mEventStatus = postVisitor.mEventStatus;
1296     // If the DOM event was created during event flow.
1297     if (!preVisitor.mDOMEvent && postVisitor.mDOMEvent) {
1298       preVisitor.mDOMEvent = postVisitor.mDOMEvent;
1299     }
1300   }
1301
1302   if (!externalDOMEvent && preVisitor.mDOMEvent) {
1303     // A dom::Event was created while dispatching the event.
1304     // Duplicate private data if someone holds a pointer to it.
1305     nsrefcnt rc = 0;
1306     NS_RELEASE2(preVisitor.mDOMEvent, rc);
1307     if (preVisitor.mDOMEvent) {
1308       preVisitor.mDOMEvent->DuplicatePrivateData();
1309     }
1310   }
1311
1312   if (aEventStatus) {
1313     *aEventStatus = preVisitor.mEventStatus;
1314   }
1315
1316   if (cd.IsMainThread() && chain.Capacity() == kCachedMainThreadChainSize &&
1317       sCachedMainThreadChains) {
1318     if (sCachedMainThreadChains->mChain1.Capacity() !=
1319         kCachedMainThreadChainSize) {
1320       chain.ClearAndRetainStorage();
1321       chain.SwapElements(sCachedMainThreadChains->mChain1);
1322     } else if (sCachedMainThreadChains->mChain2.Capacity() !=
1323                kCachedMainThreadChainSize) {
1324       chain.ClearAndRetainStorage();
1325       chain.SwapElements(sCachedMainThreadChains->mChain2);
1326     }
1327   }
1328
1329   return rv;
1330 }
1331
1332 /* static */
1333 nsresult EventDispatcher::DispatchDOMEvent(EventTarget* aTarget,
1334                                            WidgetEvent* aEvent,
1335                                            Event* aDOMEvent,
1336                                            nsPresContext* aPresContext,
1337                                            nsEventStatus* aEventStatus) {
1338   if (aDOMEvent) {
1339     WidgetEvent* innerEvent = aDOMEvent->WidgetEventPtr();
1340     NS_ENSURE_TRUE(innerEvent, NS_ERROR_ILLEGAL_VALUE);
1341
1342     // Don't modify the event if it's being dispatched right now.
1343     if (innerEvent->mFlags.mIsBeingDispatched) {
1344       return NS_ERROR_DOM_INVALID_STATE_ERR;
1345     }
1346
1347     bool dontResetTrusted = false;
1348     if (innerEvent->mFlags.mDispatchedAtLeastOnce) {
1349       innerEvent->mTarget = nullptr;
1350       innerEvent->mOriginalTarget = nullptr;
1351     } else {
1352       dontResetTrusted = aDOMEvent->IsTrusted();
1353     }
1354
1355     if (!dontResetTrusted) {
1356       // Check security state to determine if dispatcher is trusted
1357       bool trusted = NS_IsMainThread()
1358                          ? nsContentUtils::LegacyIsCallerChromeOrNativeCode()
1359                          : IsCurrentThreadRunningChromeWorker();
1360       aDOMEvent->SetTrusted(trusted);
1361     }
1362
1363     return EventDispatcher::Dispatch(aTarget, aPresContext, innerEvent,
1364                                      aDOMEvent, aEventStatus);
1365   } else if (aEvent) {
1366     return EventDispatcher::Dispatch(aTarget, aPresContext, aEvent, aDOMEvent,
1367                                      aEventStatus);
1368   }
1369   return NS_ERROR_ILLEGAL_VALUE;
1370 }
1371
1372 /* static */ already_AddRefed<dom::Event> EventDispatcher::CreateEvent(
1373     EventTarget* aOwner, nsPresContext* aPresContext, WidgetEvent* aEvent,
1374     const nsAString& aEventType, CallerType aCallerType) {
1375   if (aEvent) {
1376     switch (aEvent->mClass) {
1377       case eMutationEventClass:
1378         return NS_NewDOMMutationEvent(aOwner, aPresContext,
1379                                       aEvent->AsMutationEvent());
1380       case eGUIEventClass:
1381       case eScrollPortEventClass:
1382       case eUIEventClass:
1383         return NS_NewDOMUIEvent(aOwner, aPresContext, aEvent->AsGUIEvent());
1384       case eScrollAreaEventClass:
1385         return NS_NewDOMScrollAreaEvent(aOwner, aPresContext,
1386                                         aEvent->AsScrollAreaEvent());
1387       case eKeyboardEventClass:
1388         return NS_NewDOMKeyboardEvent(aOwner, aPresContext,
1389                                       aEvent->AsKeyboardEvent());
1390       case eCompositionEventClass:
1391         return NS_NewDOMCompositionEvent(aOwner, aPresContext,
1392                                          aEvent->AsCompositionEvent());
1393       case eMouseEventClass:
1394         return NS_NewDOMMouseEvent(aOwner, aPresContext,
1395                                    aEvent->AsMouseEvent());
1396       case eFocusEventClass:
1397         return NS_NewDOMFocusEvent(aOwner, aPresContext,
1398                                    aEvent->AsFocusEvent());
1399       case eMouseScrollEventClass:
1400         return NS_NewDOMMouseScrollEvent(aOwner, aPresContext,
1401                                          aEvent->AsMouseScrollEvent());
1402       case eWheelEventClass:
1403         return NS_NewDOMWheelEvent(aOwner, aPresContext,
1404                                    aEvent->AsWheelEvent());
1405       case eEditorInputEventClass:
1406         return NS_NewDOMInputEvent(aOwner, aPresContext,
1407                                    aEvent->AsEditorInputEvent());
1408       case eLegacyTextEventClass:
1409         return NS_NewDOMTextEvent(aOwner, aPresContext,
1410                                   aEvent->AsLegacyTextEvent());
1411       case eDragEventClass:
1412         return NS_NewDOMDragEvent(aOwner, aPresContext, aEvent->AsDragEvent());
1413       case eClipboardEventClass:
1414         return NS_NewDOMClipboardEvent(aOwner, aPresContext,
1415                                        aEvent->AsClipboardEvent());
1416       case eSMILTimeEventClass:
1417         return NS_NewDOMTimeEvent(aOwner, aPresContext,
1418                                   aEvent->AsSMILTimeEvent());
1419       case eCommandEventClass:
1420         return NS_NewDOMCommandEvent(aOwner, aPresContext,
1421                                      aEvent->AsCommandEvent());
1422       case eSimpleGestureEventClass:
1423         return NS_NewDOMSimpleGestureEvent(aOwner, aPresContext,
1424                                            aEvent->AsSimpleGestureEvent());
1425       case ePointerEventClass:
1426         return NS_NewDOMPointerEvent(aOwner, aPresContext,
1427                                      aEvent->AsPointerEvent());
1428       case eTouchEventClass:
1429         return NS_NewDOMTouchEvent(aOwner, aPresContext,
1430                                    aEvent->AsTouchEvent());
1431       case eTransitionEventClass:
1432         return NS_NewDOMTransitionEvent(aOwner, aPresContext,
1433                                         aEvent->AsTransitionEvent());
1434       case eAnimationEventClass:
1435         return NS_NewDOMAnimationEvent(aOwner, aPresContext,
1436                                        aEvent->AsAnimationEvent());
1437       default:
1438         // For all other types of events, create a vanilla event object.
1439         return NS_NewDOMEvent(aOwner, aPresContext, aEvent);
1440     }
1441   }
1442
1443   // And if we didn't get an event, check the type argument.
1444
1445   if (aEventType.LowerCaseEqualsLiteral("mouseevent") ||
1446       aEventType.LowerCaseEqualsLiteral("mouseevents")) {
1447     return NS_NewDOMMouseEvent(aOwner, aPresContext, nullptr);
1448   }
1449   if (aEventType.LowerCaseEqualsLiteral("dragevent")) {
1450     return NS_NewDOMDragEvent(aOwner, aPresContext, nullptr);
1451   }
1452   if (aEventType.LowerCaseEqualsLiteral("keyboardevent")) {
1453     return NS_NewDOMKeyboardEvent(aOwner, aPresContext, nullptr);
1454   }
1455   if (aEventType.LowerCaseEqualsLiteral("compositionevent")) {
1456     return NS_NewDOMCompositionEvent(aOwner, aPresContext, nullptr);
1457   }
1458   if (aEventType.LowerCaseEqualsLiteral("textevent")) {
1459     if (!StaticPrefs::dom_events_textevent_enabled()) {
1460       return NS_NewDOMCompositionEvent(aOwner, aPresContext, nullptr);
1461     }
1462     return NS_NewDOMTextEvent(aOwner, aPresContext, nullptr);
1463   }
1464   if (aEventType.LowerCaseEqualsLiteral("mutationevent") ||
1465       aEventType.LowerCaseEqualsLiteral("mutationevents")) {
1466     return NS_NewDOMMutationEvent(aOwner, aPresContext, nullptr);
1467   }
1468   if (aEventType.LowerCaseEqualsLiteral("deviceorientationevent")) {
1469     DeviceOrientationEventInit init;
1470     RefPtr<Event> event =
1471         DeviceOrientationEvent::Constructor(aOwner, u""_ns, init);
1472     event->MarkUninitialized();
1473     return event.forget();
1474   }
1475   if (aEventType.LowerCaseEqualsLiteral("devicemotionevent")) {
1476     return NS_NewDOMDeviceMotionEvent(aOwner, aPresContext, nullptr);
1477   }
1478   if (aEventType.LowerCaseEqualsLiteral("uievent") ||
1479       aEventType.LowerCaseEqualsLiteral("uievents")) {
1480     return NS_NewDOMUIEvent(aOwner, aPresContext, nullptr);
1481   }
1482   if (aEventType.LowerCaseEqualsLiteral("event") ||
1483       aEventType.LowerCaseEqualsLiteral("events") ||
1484       aEventType.LowerCaseEqualsLiteral("htmlevents") ||
1485       aEventType.LowerCaseEqualsLiteral("svgevents")) {
1486     return NS_NewDOMEvent(aOwner, aPresContext, nullptr);
1487   }
1488   if (aEventType.LowerCaseEqualsLiteral("messageevent")) {
1489     RefPtr<Event> event = new MessageEvent(aOwner, aPresContext, nullptr);
1490     return event.forget();
1491   }
1492   if (aEventType.LowerCaseEqualsLiteral("beforeunloadevent")) {
1493     return NS_NewDOMBeforeUnloadEvent(aOwner, aPresContext, nullptr);
1494   }
1495   if (aEventType.LowerCaseEqualsLiteral("touchevent") &&
1496       TouchEvent::LegacyAPIEnabled(
1497           nsContentUtils::GetDocShellForEventTarget(aOwner),
1498           aCallerType == CallerType::System)) {
1499     return NS_NewDOMTouchEvent(aOwner, aPresContext, nullptr);
1500   }
1501   if (aEventType.LowerCaseEqualsLiteral("hashchangeevent")) {
1502     HashChangeEventInit init;
1503     RefPtr<Event> event = HashChangeEvent::Constructor(aOwner, u""_ns, init);
1504     event->MarkUninitialized();
1505     return event.forget();
1506   }
1507   if (aEventType.LowerCaseEqualsLiteral("customevent")) {
1508     return NS_NewDOMCustomEvent(aOwner, aPresContext, nullptr);
1509   }
1510   if (aEventType.LowerCaseEqualsLiteral("storageevent")) {
1511     RefPtr<Event> event =
1512         StorageEvent::Constructor(aOwner, u""_ns, StorageEventInit());
1513     event->MarkUninitialized();
1514     return event.forget();
1515   }
1516   if (aEventType.LowerCaseEqualsLiteral("focusevent")) {
1517     RefPtr<Event> event = NS_NewDOMFocusEvent(aOwner, aPresContext, nullptr);
1518     event->MarkUninitialized();
1519     return event.forget();
1520   }
1521
1522   // Only allow these events for chrome
1523   if (aCallerType == CallerType::System) {
1524     if (aEventType.LowerCaseEqualsLiteral("simplegestureevent")) {
1525       return NS_NewDOMSimpleGestureEvent(aOwner, aPresContext, nullptr);
1526     }
1527     if (aEventType.LowerCaseEqualsLiteral("xulcommandevent") ||
1528         aEventType.LowerCaseEqualsLiteral("xulcommandevents")) {
1529       return NS_NewDOMXULCommandEvent(aOwner, aPresContext, nullptr);
1530     }
1531   }
1532
1533   // NEW EVENT TYPES SHOULD NOT BE ADDED HERE; THEY SHOULD USE ONLY EVENT
1534   // CONSTRUCTORS
1535
1536   return nullptr;
1537 }
1538
1539 struct CurrentTargetPathInfo {
1540   uint32_t mIndex;
1541   int32_t mHiddenSubtreeLevel;
1542 };
1543
1544 static CurrentTargetPathInfo TargetPathInfo(
1545     const nsTArray<EventTargetChainItem>& aEventPath,
1546     const EventTarget& aCurrentTarget) {
1547   int32_t currentTargetHiddenSubtreeLevel = 0;
1548   for (uint32_t index = aEventPath.Length(); index--;) {
1549     const EventTargetChainItem& item = aEventPath.ElementAt(index);
1550     if (item.PreHandleEventOnly()) {
1551       continue;
1552     }
1553
1554     if (item.IsRootOfClosedTree()) {
1555       currentTargetHiddenSubtreeLevel++;
1556     }
1557
1558     if (item.CurrentTarget() == &aCurrentTarget) {
1559       return {index, currentTargetHiddenSubtreeLevel};
1560     }
1561
1562     if (item.IsSlotInClosedTree()) {
1563       currentTargetHiddenSubtreeLevel--;
1564     }
1565   }
1566   MOZ_ASSERT_UNREACHABLE("No target found?");
1567   return {0, 0};
1568 }
1569
1570 // https://dom.spec.whatwg.org/#dom-event-composedpath
1571 void EventDispatcher::GetComposedPathFor(WidgetEvent* aEvent,
1572                                          nsTArray<RefPtr<EventTarget>>& aPath) {
1573   MOZ_ASSERT(aPath.IsEmpty());
1574   nsTArray<EventTargetChainItem>* path = aEvent->mPath;
1575   if (!path || path->IsEmpty() || !aEvent->mCurrentTarget) {
1576     return;
1577   }
1578
1579   EventTarget* currentTarget =
1580       aEvent->mCurrentTarget->GetTargetForEventTargetChain();
1581   if (!currentTarget) {
1582     return;
1583   }
1584
1585   CurrentTargetPathInfo currentTargetInfo =
1586       TargetPathInfo(*path, *currentTarget);
1587
1588   {
1589     int32_t maxHiddenLevel = currentTargetInfo.mHiddenSubtreeLevel;
1590     int32_t currentHiddenLevel = currentTargetInfo.mHiddenSubtreeLevel;
1591     for (uint32_t index = currentTargetInfo.mIndex; index--;) {
1592       EventTargetChainItem& item = path->ElementAt(index);
1593       if (item.PreHandleEventOnly()) {
1594         continue;
1595       }
1596
1597       if (item.IsRootOfClosedTree()) {
1598         currentHiddenLevel++;
1599       }
1600
1601       if (currentHiddenLevel <= maxHiddenLevel) {
1602         aPath.AppendElement(item.CurrentTarget()->GetTargetForDOMEvent());
1603       }
1604
1605       if (item.IsChromeHandler()) {
1606         break;
1607       }
1608
1609       if (item.IsSlotInClosedTree()) {
1610         currentHiddenLevel--;
1611         maxHiddenLevel = std::min(maxHiddenLevel, currentHiddenLevel);
1612       }
1613     }
1614
1615     aPath.Reverse();
1616   }
1617
1618   aPath.AppendElement(currentTarget->GetTargetForDOMEvent());
1619
1620   {
1621     int32_t maxHiddenLevel = currentTargetInfo.mHiddenSubtreeLevel;
1622     int32_t currentHiddenLevel = currentTargetInfo.mHiddenSubtreeLevel;
1623     for (uint32_t index = currentTargetInfo.mIndex + 1; index < path->Length();
1624          ++index) {
1625       EventTargetChainItem& item = path->ElementAt(index);
1626       if (item.PreHandleEventOnly()) {
1627         continue;
1628       }
1629
1630       if (item.IsSlotInClosedTree()) {
1631         currentHiddenLevel++;
1632       }
1633
1634       if (item.IsChromeHandler()) {
1635         break;
1636       }
1637
1638       if (currentHiddenLevel <= maxHiddenLevel) {
1639         aPath.AppendElement(item.CurrentTarget()->GetTargetForDOMEvent());
1640       }
1641
1642       if (item.IsRootOfClosedTree()) {
1643         currentHiddenLevel--;
1644         maxHiddenLevel = std::min(maxHiddenLevel, currentHiddenLevel);
1645       }
1646     }
1647   }
1648 }
1649
1650 void EventChainPreVisitor::IgnoreCurrentTargetBecauseOfShadowDOMRetargeting() {
1651   mCanHandle = false;
1652   mIgnoreBecauseOfShadowDOM = true;
1653
1654   EventTarget* target = nullptr;
1655
1656   auto getWindow = [this]() -> nsPIDOMWindowOuter* {
1657     nsINode* node = nsINode::FromEventTargetOrNull(this->mParentTarget);
1658     if (!node) {
1659       return nullptr;
1660     }
1661     Document* doc = node->GetComposedDoc();
1662     if (!doc) {
1663       return nullptr;
1664     }
1665
1666     return doc->GetWindow();
1667   };
1668
1669   // The HTMLEditor is registered to nsWindowRoot, so we
1670   // want to dispatch events to it.
1671   if (nsCOMPtr<nsPIDOMWindowOuter> win = getWindow()) {
1672     target = win->GetParentTarget();
1673   }
1674   SetParentTarget(target, false);
1675
1676   mEventTargetAtParent = nullptr;
1677 }
1678
1679 }  // namespace mozilla