content/browser/child_process_launcher.cc

   1 // Copyright 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/child_process_launcher.h"
   6
   7 #include "base/bind.h"
   8 #include "base/command_line.h"
   9 #include "base/files/file_util.h"
  10 #include "base/i18n/icu_util.h"
  11 #include "base/logging.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/metrics/histogram.h"
  14 #include "base/process/process.h"
  15 #include "base/profiler/scoped_tracker.h"
  16 #include "base/synchronization/lock.h"
  17 #include "base/threading/thread.h"
  18 #include "content/public/browser/content_browser_client.h"
  19 #include "content/public/common/content_descriptors.h"
  20 #include "content/public/common/content_switches.h"
  21 #include "content/public/common/result_codes.h"
  22 #include "content/public/common/sandboxed_process_launcher_delegate.h"
  23
  24 #if defined(OS_WIN)
  25 #include "base/files/file_path.h"
  26 #include "content/common/sandbox_win.h"
  27 #include "content/public/common/sandbox_init.h"
  28 #elif defined(OS_MACOSX)
  29 #include "content/browser/bootstrap_sandbox_mac.h"
  30 #include "content/browser/browser_io_surface_manager_mac.h"
  31 #include "content/browser/mach_broker_mac.h"
  32 #include "sandbox/mac/bootstrap_sandbox.h"
  33 #elif defined(OS_ANDROID)
  34 #include "base/android/jni_android.h"
  35 #include "content/browser/android/child_process_launcher_android.h"
  36 #elif defined(OS_POSIX)
  37 #include "base/memory/shared_memory.h"
  38 #include "base/memory/singleton.h"
  39 #include "content/browser/renderer_host/render_sandbox_host_linux.h"
  40 #include "content/browser/zygote_host/zygote_host_impl_linux.h"
  41 #include "content/common/child_process_sandbox_support_impl_linux.h"
  42 #endif
  43
  44 #if defined(OS_POSIX)
  45 #include "base/posix/global_descriptors.h"
  46 #include "content/browser/file_descriptor_info_impl.h"
  47 #include "gin/v8_initializer.h"
  48 #endif
  49
  50 namespace content {
  51
  52 namespace {
  53
  54 typedef base::Callback<void(bool,
  55 #if defined(OS_ANDROID)
  56                             base::ScopedFD,
  57 #endif
  58                             base::Process)> NotifyCallback;
  59
  60 void RecordHistogramsOnLauncherThread(base::TimeDelta launch_time) {
  61   DCHECK_CURRENTLY_ON(BrowserThread::PROCESS_LAUNCHER);
  62   // Log the launch time, separating out the first one (which will likely be
  63   // slower due to the rest of the browser initializing at the same time).
  64   static bool done_first_launch = false;
  65   if (done_first_launch) {
  66     UMA_HISTOGRAM_TIMES("MPArch.ChildProcessLaunchSubsequent", launch_time);
  67   } else {
  68     UMA_HISTOGRAM_TIMES("MPArch.ChildProcessLaunchFirst", launch_time);
  69     done_first_launch = true;
  70   }
  71 }
  72
  73 #if defined(OS_ANDROID)
  74 // TODO(sievers): Remove this by defining better what happens on what
  75 // thread in the corresponding Java code.
  76 void OnChildProcessStartedAndroid(const NotifyCallback& callback,
  77                                   BrowserThread::ID client_thread_id,
  78                                   const base::TimeTicks begin_launch_time,
  79                                   base::ScopedFD ipcfd,
  80                                   base::ProcessHandle handle) {
  81   // This can be called on the launcher thread or UI thread.
  82   base::TimeDelta launch_time = base::TimeTicks::Now() - begin_launch_time;
  83   BrowserThread::PostTask(
  84       BrowserThread::PROCESS_LAUNCHER, FROM_HERE,
  85       base::Bind(&RecordHistogramsOnLauncherThread, launch_time));
  86
  87   base::Closure callback_on_client_thread(
  88       base::Bind(callback, false, base::Passed(&ipcfd),
  89                  base::Passed(base::Process(handle))));
  90   if (BrowserThread::CurrentlyOn(client_thread_id)) {
  91     callback_on_client_thread.Run();
  92   } else {
  93     BrowserThread::PostTask(
  94         client_thread_id, FROM_HERE, callback_on_client_thread);
  95  }
  96 }
  97 #endif
  98
  99 void LaunchOnLauncherThread(const NotifyCallback& callback,
 100                             BrowserThread::ID client_thread_id,
 101                             int child_process_id,
 102                             SandboxedProcessLauncherDelegate* delegate,
 103 #if defined(OS_ANDROID)
 104                             base::ScopedFD ipcfd,
 105 #endif
 106                             base::CommandLine* cmd_line) {
 107   DCHECK_CURRENTLY_ON(BrowserThread::PROCESS_LAUNCHER);
 108   scoped_ptr<SandboxedProcessLauncherDelegate> delegate_deleter(delegate);
 109 #if defined(OS_WIN)
 110   bool use_zygote = false;
 111   bool launch_elevated = delegate->ShouldLaunchElevated();
 112 #elif defined(OS_MACOSX)
 113   bool use_zygote = false;
 114   base::EnvironmentMap env = delegate->GetEnvironment();
 115   base::ScopedFD ipcfd = delegate->TakeIpcFd();
 116 #elif defined(OS_POSIX) && !defined(OS_ANDROID)
 117   bool use_zygote = delegate->ShouldUseZygote();
 118   base::EnvironmentMap env = delegate->GetEnvironment();
 119   base::ScopedFD ipcfd = delegate->TakeIpcFd();
 120 #endif
 121   scoped_ptr<base::CommandLine> cmd_line_deleter(cmd_line);
 122   base::TimeTicks begin_launch_time = base::TimeTicks::Now();
 123
 124   base::Process process;
 125 #if defined(OS_WIN)
 126   if (launch_elevated) {
 127     base::LaunchOptions options;
 128     options.start_hidden = true;
 129     process = base::LaunchElevatedProcess(*cmd_line, options);
 130   } else {
 131     process = StartSandboxedProcess(delegate, cmd_line);
 132   }
 133 #elif defined(OS_POSIX)
 134   std::string process_type =
 135       cmd_line->GetSwitchValueASCII(switches::kProcessType);
 136   scoped_ptr<FileDescriptorInfo> files_to_register(
 137       FileDescriptorInfoImpl::Create());
 138
 139 #if defined(OS_ANDROID)
 140   files_to_register->Share(kPrimaryIPCChannel, ipcfd.get());
 141 #else
 142   files_to_register->Transfer(kPrimaryIPCChannel, ipcfd.Pass());
 143 #endif
 144 #endif
 145
 146 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 147   std::map<int, base::MemoryMappedFile::Region> regions;
 148   GetContentClient()->browser()->GetAdditionalMappedFilesForChildProcess(
 149       *cmd_line, child_process_id, files_to_register.get()
 150 #if defined(OS_ANDROID)
 151       , &regions
 152 #endif
 153       );
 154 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
 155   base::PlatformFile natives_pf =
 156       gin::V8Initializer::GetOpenNativesFileForChildProcesses(
 157           &regions[kV8NativesDataDescriptor]);
 158   DCHECK_GE(natives_pf, 0);
 159   files_to_register->Share(kV8NativesDataDescriptor, natives_pf);
 160
 161   base::MemoryMappedFile::Region snapshot_region;
 162   base::PlatformFile snapshot_pf =
 163       gin::V8Initializer::GetOpenSnapshotFileForChildProcesses(
 164           &snapshot_region);
 165   // Failure to load the V8 snapshot is not necessarily an error. V8 can start
 166   // up (slower) without the snapshot.
 167   if (snapshot_pf != -1) {
 168     files_to_register->Share(kV8SnapshotDataDescriptor, snapshot_pf);
 169     regions.insert(std::make_pair(kV8SnapshotDataDescriptor, snapshot_region));
 170   }
 171
 172   if (process_type != switches::kZygoteProcess) {
 173     cmd_line->AppendSwitch(::switches::kV8NativesPassedByFD);
 174     if (snapshot_pf != -1) {
 175       cmd_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
 176     }
 177   }
 178 #endif  // defined(V8_USE_EXTERNAL_STARTUP_DATA)
 179 #endif  // defined(OS_POSIX) && !defined(OS_MACOSX)
 180
 181 #if defined(OS_ANDROID)
 182   files_to_register->Share(
 183       kAndroidICUDataDescriptor,
 184       base::i18n::GetIcuDataFileHandle(&regions[kAndroidICUDataDescriptor]));
 185
 186   // Android WebView runs in single process, ensure that we never get here
 187   // when running in single process mode.
 188   CHECK(!cmd_line->HasSwitch(switches::kSingleProcess));
 189
 190   StartChildProcess(
 191       cmd_line->argv(), child_process_id, files_to_register.Pass(), regions,
 192       base::Bind(&OnChildProcessStartedAndroid, callback, client_thread_id,
 193                  begin_launch_time, base::Passed(&ipcfd)));
 194
 195 #elif defined(OS_POSIX)
 196   // We need to close the client end of the IPC channel to reliably detect
 197   // child termination.
 198
 199 #if !defined(OS_MACOSX)
 200   if (use_zygote) {
 201     base::ProcessHandle handle = ZygoteHostImpl::GetInstance()->ForkRequest(
 202         cmd_line->argv(), files_to_register.Pass(), process_type);
 203     process = base::Process(handle);
 204   } else
 205   // Fall through to the normal posix case below when we're not zygoting.
 206 #endif  // !defined(OS_MACOSX)
 207   {
 208     // Convert FD mapping to FileHandleMappingVector
 209     base::FileHandleMappingVector fds_to_map =
 210         files_to_register->GetMappingWithIDAdjustment(
 211             base::GlobalDescriptors::kBaseDescriptor);
 212
 213 #if !defined(OS_MACOSX)
 214     if (process_type == switches::kRendererProcess) {
 215       const int sandbox_fd =
 216           RenderSandboxHostLinux::GetInstance()->GetRendererSocket();
 217       fds_to_map.push_back(std::make_pair(
 218           sandbox_fd,
 219           GetSandboxFD()));
 220     }
 221 #endif  // defined(OS_MACOSX)
 222
 223     // Actually launch the app.
 224     base::LaunchOptions options;
 225     options.environ = env;
 226     options.fds_to_remap = &fds_to_map;
 227
 228 #if defined(OS_MACOSX)
 229     // Hold the MachBroker lock for the duration of LaunchProcess. The child
 230     // will send its task port to the parent almost immediately after startup.
 231     // The Mach message will be delivered to the parent, but updating the
 232     // record of the launch will wait until after the placeholder PID is
 233     // inserted below. This ensures that while the child process may send its
 234     // port to the parent prior to the parent leaving LaunchProcess, the
 235     // order in which the record in MachBroker is updated is correct.
 236     MachBroker* broker = MachBroker::GetInstance();
 237     broker->GetLock().Acquire();
 238
 239     // Make sure the MachBroker is running, and inform it to expect a
 240     // check-in from the new process.
 241     broker->EnsureRunning();
 242
 243     // Make sure the IOSurfaceManager service is running.
 244     BrowserIOSurfaceManager::GetInstance()->EnsureRunning();
 245
 246     const int bootstrap_sandbox_policy = delegate->GetSandboxType();
 247     if (ShouldEnableBootstrapSandbox() &&
 248         bootstrap_sandbox_policy != SANDBOX_TYPE_INVALID) {
 249       options.replacement_bootstrap_name =
 250           GetBootstrapSandbox()->server_bootstrap_name();
 251       GetBootstrapSandbox()->PrepareToForkWithPolicy(
 252           bootstrap_sandbox_policy);
 253     }
 254 #endif  // defined(OS_MACOSX)
 255
 256     process = base::LaunchProcess(*cmd_line, options);
 257
 258 #if defined(OS_MACOSX)
 259     if (ShouldEnableBootstrapSandbox() &&
 260         bootstrap_sandbox_policy != SANDBOX_TYPE_INVALID) {
 261       GetBootstrapSandbox()->FinishedFork(process.Handle());
 262     }
 263
 264     if (process.IsValid())
 265       broker->AddPlaceholderForPid(process.Pid(), child_process_id);
 266
 267     // After updating the broker, release the lock and let the child's
 268     // messasge be processed on the broker's thread.
 269     broker->GetLock().Release();
 270 #endif  // defined(OS_MACOSX)
 271   }
 272 #endif  // else defined(OS_POSIX)
 273 #if !defined(OS_ANDROID)
 274   if (process.IsValid()) {
 275     RecordHistogramsOnLauncherThread(base::TimeTicks::Now() -
 276                                      begin_launch_time);
 277   }
 278   BrowserThread::PostTask(client_thread_id, FROM_HERE,
 279                           base::Bind(callback,
 280                                      use_zygote,
 281                                      base::Passed(&process)));
 282 #endif  // !defined(OS_ANDROID)
 283 }
 284
 285 void TerminateOnLauncherThread(bool zygote, base::Process process) {
 286   DCHECK_CURRENTLY_ON(BrowserThread::PROCESS_LAUNCHER);
 287 #if defined(OS_ANDROID)
 288   VLOG(1) << "ChromeProcess: Stopping process with handle "
 289           << process.Handle();
 290   StopChildProcess(process.Handle());
 291 #else
 292   // Client has gone away, so just kill the process.  Using exit code 0
 293   // means that UMA won't treat this as a crash.
 294   process.Terminate(RESULT_CODE_NORMAL_EXIT, false);
 295   // On POSIX, we must additionally reap the child.
 296 #if defined(OS_POSIX)
 297 #if !defined(OS_MACOSX)
 298   if (zygote) {
 299     // If the renderer was created via a zygote, we have to proxy the reaping
 300     // through the zygote process.
 301     ZygoteHostImpl::GetInstance()->EnsureProcessTerminated(process.Handle());
 302   } else
 303 #endif  // !OS_MACOSX
 304   base::EnsureProcessTerminated(process.Pass());
 305 #endif  // OS_POSIX
 306 #endif  // defined(OS_ANDROID)
 307 }
 308
 309 void SetProcessBackgroundedOnLauncherThread(base::Process process,
 310                                             bool background) {
 311   DCHECK_CURRENTLY_ON(BrowserThread::PROCESS_LAUNCHER);
 312 #if defined(OS_MACOSX)
 313   MachBroker* broker = MachBroker::GetInstance();
 314   mach_port_t task_port = broker->TaskForPid(process.Pid());
 315   if (task_port != TASK_NULL) {
 316     process.SetProcessBackgrounded(task_port, background);
 317   }
 318 #else
 319   process.SetProcessBackgrounded(background);
 320 #endif  // defined(OS_MACOSX)
 321 #if defined(OS_ANDROID)
 322   SetChildProcessInForeground(process.Handle(), !background);
 323 #endif
 324 }
 325
 326 }  // anonymous namespace
 327
 328 ChildProcessLauncher::ChildProcessLauncher(
 329     SandboxedProcessLauncherDelegate* delegate,
 330     base::CommandLine* cmd_line,
 331     int child_process_id,
 332     Client* client,
 333     bool terminate_on_shutdown)
 334     : client_(client),
 335       termination_status_(base::TERMINATION_STATUS_NORMAL_TERMINATION),
 336       exit_code_(RESULT_CODE_NORMAL_EXIT),
 337       zygote_(false),
 338       starting_(true),
 339 #if defined(ADDRESS_SANITIZER) || defined(LEAK_SANITIZER) ||  \
 340     defined(MEMORY_SANITIZER) || defined(THREAD_SANITIZER) || \
 341     defined(UNDEFINED_SANITIZER)
 342       terminate_child_on_shutdown_(false),
 343 #else
 344       terminate_child_on_shutdown_(terminate_on_shutdown),
 345 #endif
 346       weak_factory_(this) {
 347   DCHECK(CalledOnValidThread());
 348   CHECK(BrowserThread::GetCurrentThreadIdentifier(&client_thread_id_));
 349   Launch(delegate, cmd_line, child_process_id);
 350 }
 351
 352 ChildProcessLauncher::~ChildProcessLauncher() {
 353   DCHECK(CalledOnValidThread());
 354   if (process_.IsValid() && terminate_child_on_shutdown_) {
 355     // On Posix, EnsureProcessTerminated can lead to 2 seconds of sleep!  So
 356     // don't this on the UI/IO threads.
 357     BrowserThread::PostTask(BrowserThread::PROCESS_LAUNCHER, FROM_HERE,
 358                             base::Bind(&TerminateOnLauncherThread, zygote_,
 359                                        base::Passed(&process_)));
 360   }
 361 }
 362
 363 void ChildProcessLauncher::Launch(
 364     SandboxedProcessLauncherDelegate* delegate,
 365     base::CommandLine* cmd_line,
 366     int child_process_id) {
 367   DCHECK(CalledOnValidThread());
 368
 369 #if defined(OS_ANDROID)
 370   // Android only supports renderer, sandboxed utility and gpu.
 371   std::string process_type =
 372       cmd_line->GetSwitchValueASCII(switches::kProcessType);
 373   CHECK(process_type == switches::kGpuProcess ||
 374         process_type == switches::kRendererProcess ||
 375         process_type == switches::kUtilityProcess)
 376       << "Unsupported process type: " << process_type;
 377
 378   // Non-sandboxed utility or renderer process are currently not supported.
 379   DCHECK(process_type == switches::kGpuProcess ||
 380          !cmd_line->HasSwitch(switches::kNoSandbox));
 381
 382   // We need to close the client end of the IPC channel to reliably detect
 383   // child termination. We will close this fd after we create the child
 384   // process which is asynchronous on Android.
 385   base::ScopedFD ipcfd(delegate->TakeIpcFd().release());
 386 #endif
 387   NotifyCallback reply_callback(base::Bind(&ChildProcessLauncher::DidLaunch,
 388                                            weak_factory_.GetWeakPtr(),
 389                                            terminate_child_on_shutdown_));
 390   BrowserThread::PostTask(
 391       BrowserThread::PROCESS_LAUNCHER, FROM_HERE,
 392       base::Bind(&LaunchOnLauncherThread, reply_callback, client_thread_id_,
 393                  child_process_id, delegate,
 394 #if defined(OS_ANDROID)
 395                  base::Passed(&ipcfd),
 396 #endif
 397                  cmd_line));
 398 }
 399
 400 void ChildProcessLauncher::UpdateTerminationStatus(bool known_dead) {
 401   DCHECK(CalledOnValidThread());
 402 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
 403   if (zygote_) {
 404     termination_status_ = ZygoteHostImpl::GetInstance()->
 405         GetTerminationStatus(process_.Handle(), known_dead, &exit_code_);
 406   } else if (known_dead) {
 407     termination_status_ =
 408         base::GetKnownDeadTerminationStatus(process_.Handle(), &exit_code_);
 409   } else {
 410 #elif defined(OS_MACOSX)
 411   if (known_dead) {
 412     termination_status_ =
 413         base::GetKnownDeadTerminationStatus(process_.Handle(), &exit_code_);
 414   } else {
 415 #elif defined(OS_ANDROID)
 416   if (IsChildProcessOomProtected(process_.Handle())) {
 417     termination_status_ = base::TERMINATION_STATUS_OOM_PROTECTED;
 418   } else {
 419 #else
 420   {
 421 #endif
 422     termination_status_ =
 423       base::GetTerminationStatus(process_.Handle(), &exit_code_);
 424   }
 425 }
 426
 427 void ChildProcessLauncher::SetProcessBackgrounded(bool background) {
 428   DCHECK(CalledOnValidThread());
 429   base::Process to_pass = process_.Duplicate();
 430   BrowserThread::PostTask(BrowserThread::PROCESS_LAUNCHER, FROM_HERE,
 431                           base::Bind(&SetProcessBackgroundedOnLauncherThread,
 432                                      base::Passed(&to_pass), background));
 433 }
 434
 435 void ChildProcessLauncher::DidLaunch(
 436     base::WeakPtr<ChildProcessLauncher> instance,
 437     bool terminate_on_shutdown,
 438     bool zygote,
 439 #if defined(OS_ANDROID)
 440     base::ScopedFD ipcfd,
 441 #endif
 442     base::Process process) {
 443   if (!process.IsValid())
 444     LOG(ERROR) << "Failed to launch child process";
 445
 446   // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/465841
 447   // is fixed.
 448   tracked_objects::ScopedTracker tracking_profile1(
 449       FROM_HERE_WITH_EXPLICIT_FUNCTION(
 450           "465841 ChildProcessLauncher::Context::Notify::Start"));
 451
 452   if (instance.get()) {
 453     instance->Notify(zygote,
 454 #if defined(OS_ANDROID)
 455                      ipcfd.Pass(),
 456 #endif
 457                      process.Pass());
 458   } else {
 459     // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/465841
 460     // is fixed.
 461     tracked_objects::ScopedTracker tracking_profile4(
 462         FROM_HERE_WITH_EXPLICIT_FUNCTION(
 463             "465841 ChildProcessLauncher::Context::Notify::ProcessTerminate"));
 464     if (process.IsValid() && terminate_on_shutdown) {
 465       // On Posix, EnsureProcessTerminated can lead to 2 seconds of sleep!  So
 466       // don't this on the UI/IO threads.
 467       BrowserThread::PostTask(BrowserThread::PROCESS_LAUNCHER, FROM_HERE,
 468                               base::Bind(&TerminateOnLauncherThread, zygote,
 469                                          base::Passed(&process)));
 470     }
 471   }
 472 }
 473
 474 void ChildProcessLauncher::Notify(
 475     bool zygote,
 476 #if defined(OS_ANDROID)
 477     base::ScopedFD ipcfd,
 478 #endif
 479     base::Process process) {
 480   DCHECK(CalledOnValidThread());
 481   starting_ = false;
 482   process_ = process.Pass();
 483
 484 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
 485   zygote_ = zygote;
 486 #endif
 487   if (process_.IsValid()) {
 488     // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/465841
 489     // is fixed.
 490     tracked_objects::ScopedTracker tracking_profile2(
 491         FROM_HERE_WITH_EXPLICIT_FUNCTION(
 492             "465841 ChildProcessLauncher::Context::Notify::ProcessLaunched"));
 493     client_->OnProcessLaunched();
 494   } else {
 495     // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/465841
 496     // is fixed.
 497     tracked_objects::ScopedTracker tracking_profile3(
 498         FROM_HERE_WITH_EXPLICIT_FUNCTION(
 499             "465841 ChildProcessLauncher::Context::Notify::ProcessFailed"));
 500     client_->OnProcessLaunchFailed();
 501   }
 502 }
 503
 504 bool ChildProcessLauncher::IsStarting() {
 505   // TODO(crbug.com/469248): This fails in some tests.
 506   // DCHECK(CalledOnValidThread());
 507   return starting_;
 508 }
 509
 510 const base::Process& ChildProcessLauncher::GetProcess() const {
 511   // TODO(crbug.com/469248): This fails in some tests.
 512   // DCHECK(CalledOnValidThread());
 513   return process_;
 514 }
 515
 516 base::TerminationStatus ChildProcessLauncher::GetChildTerminationStatus(
 517     bool known_dead,
 518     int* exit_code) {
 519   DCHECK(CalledOnValidThread());
 520   if (!process_.IsValid()) {
 521     // Process is already gone, so return the cached termination status.
 522     if (exit_code)
 523       *exit_code = exit_code_;
 524     return termination_status_;
 525   }
 526
 527   UpdateTerminationStatus(known_dead);
 528   if (exit_code)
 529     *exit_code = exit_code_;
 530
 531   // POSIX: If the process crashed, then the kernel closed the socket
 532   // for it and so the child has already died by the time we get
 533   // here. Since GetTerminationStatus called waitpid with WNOHANG,
 534   // it'll reap the process.  However, if GetTerminationStatus didn't
 535   // reap the child (because it was still running), we'll need to
 536   // Terminate via ProcessWatcher. So we can't close the handle here.
 537   if (termination_status_ != base::TERMINATION_STATUS_STILL_RUNNING)
 538     process_.Close();
 539
 540   return termination_status_;
 541 }
 542
 543 ChildProcessLauncher::Client* ChildProcessLauncher::ReplaceClientForTest(
 544     Client* client) {
 545   Client* ret = client_;
 546   client_ = client;
 547   return ret;
 548 }
 549
 550 }  // namespace content