media/midi/midi_manager_win.cc

   1 // Copyright 2013 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 "media/midi/midi_manager_win.h"
   6
   7 #include <windows.h>
   8
   9 // Prevent unnecessary functions from being included from <mmsystem.h>
  10 #define MMNODRV
  11 #define MMNOSOUND
  12 #define MMNOWAVE
  13 #define MMNOAUX
  14 #define MMNOMIXER
  15 #define MMNOTIMER
  16 #define MMNOJOY
  17 #define MMNOMCI
  18 #define MMNOMMIO
  19 #include <mmsystem.h>
  20
  21 #include <algorithm>
  22 #include <string>
  23 #include "base/bind.h"
  24 #include "base/message_loop/message_loop.h"
  25 #include "base/strings/string_number_conversions.h"
  26 #include "base/strings/utf_string_conversions.h"
  27 #include "base/threading/thread.h"
  28 #include "media/midi/midi_message_queue.h"
  29 #include "media/midi/midi_message_util.h"
  30 #include "media/midi/midi_port_info.h"
  31
  32 namespace media {
  33 namespace {
  34
  35 std::string GetInErrorMessage(MMRESULT result) {
  36   wchar_t text[MAXERRORLENGTH];
  37   MMRESULT get_result = midiInGetErrorText(result, text, arraysize(text));
  38   if (get_result != MMSYSERR_NOERROR) {
  39     DLOG(ERROR) << "Failed to get error message."
  40                 << " original error: " << result
  41                 << " midiInGetErrorText error: " << get_result;
  42     return std::string();
  43   }
  44   return base::WideToUTF8(text);
  45 }
  46
  47 std::string GetOutErrorMessage(MMRESULT result) {
  48   wchar_t text[MAXERRORLENGTH];
  49   MMRESULT get_result = midiOutGetErrorText(result, text, arraysize(text));
  50   if (get_result != MMSYSERR_NOERROR) {
  51     DLOG(ERROR) << "Failed to get error message."
  52                 << " original error: " << result
  53                 << " midiOutGetErrorText error: " << get_result;
  54     return std::string();
  55   }
  56   return base::WideToUTF8(text);
  57 }
  58
  59 class MIDIHDRDeleter {
  60  public:
  61   void operator()(MIDIHDR* header) {
  62     if (!header)
  63       return;
  64     delete[] static_cast<char*>(header->lpData);
  65     header->lpData = NULL;
  66     header->dwBufferLength = 0;
  67     delete header;
  68   }
  69 };
  70
  71 typedef scoped_ptr<MIDIHDR, MIDIHDRDeleter> ScopedMIDIHDR;
  72
  73 ScopedMIDIHDR CreateMIDIHDR(size_t size) {
  74   ScopedMIDIHDR header(new MIDIHDR);
  75   ZeroMemory(header.get(), sizeof(*header));
  76   header->lpData = new char[size];
  77   header->dwBufferLength = size;
  78   return header.Pass();
  79 }
  80
  81 void SendShortMidiMessageInternal(HMIDIOUT midi_out_handle,
  82                                   const std::vector<uint8>& message) {
  83   if (message.size() >= 4)
  84     return;
  85
  86   DWORD packed_message = 0;
  87   for (size_t i = 0; i < message.size(); ++i)
  88     packed_message |= (static_cast<uint32>(message[i]) << (i * 8));
  89   MMRESULT result = midiOutShortMsg(midi_out_handle, packed_message);
  90   DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
  91       << "Failed to output short message: " << GetOutErrorMessage(result);
  92 }
  93
  94 void SendLongMidiMessageInternal(HMIDIOUT midi_out_handle,
  95                                  const std::vector<uint8>& message) {
  96   // Implementation note:
  97   // Sending long MIDI message can be performed synchronously or asynchronously
  98   // depending on the driver. There are 2 options to support both cases:
  99   // 1) Call midiOutLongMsg() API and wait for its completion within this
 100   //   function. In this approach, we can avoid memory copy by directly pointing
 101   //   |message| as the data buffer to be sent.
 102   // 2) Allocate a buffer and copy |message| to it, then call midiOutLongMsg()
 103   //   API. The buffer will be freed in the MOM_DONE event hander, which tells
 104   //   us that the task of midiOutLongMsg() API is completed.
 105   // Here we choose option 2) in favor of asynchronous design.
 106
 107   // Note for built-in USB-MIDI driver:
 108   // From an observation on Windows 7/8.1 with a USB-MIDI keyboard,
 109   // midiOutLongMsg() will be always blocked. Sending 64 bytes or less data
 110   // takes roughly 300 usecs. Sending 2048 bytes or more data takes roughly
 111   // |message.size() / (75 * 1024)| secs in practice. Here we put 60 KB size
 112   // limit on SysEx message, with hoping that midiOutLongMsg will be blocked at
 113   // most 1 sec or so with a typical USB-MIDI device.
 114   const size_t kSysExSizeLimit = 60 * 1024;
 115   if (message.size() >= kSysExSizeLimit) {
 116     DVLOG(1) << "Ingnoreing SysEx message due to the size limit"
 117              << ", size = " << message.size();
 118     return;
 119   }
 120
 121   ScopedMIDIHDR midi_header(CreateMIDIHDR(message.size()));
 122   for (size_t i = 0; i < message.size(); ++i)
 123     midi_header->lpData[i] = static_cast<char>(message[i]);
 124
 125   MMRESULT result = midiOutPrepareHeader(
 126       midi_out_handle, midi_header.get(), sizeof(*midi_header));
 127   if (result != MMSYSERR_NOERROR) {
 128     DLOG(ERROR) << "Failed to prepare output buffer: "
 129                 << GetOutErrorMessage(result);
 130     return;
 131   }
 132
 133   result = midiOutLongMsg(
 134       midi_out_handle, midi_header.get(), sizeof(*midi_header));
 135   if (result != MMSYSERR_NOERROR) {
 136     DLOG(ERROR) << "Failed to output long message: "
 137                 << GetOutErrorMessage(result);
 138     result = midiOutUnprepareHeader(
 139         midi_out_handle, midi_header.get(), sizeof(*midi_header));
 140     DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 141         << "Failed to uninitialize output buffer: "
 142         << GetOutErrorMessage(result);
 143     return;
 144   }
 145
 146   // The ownership of |midi_header| is moved to MOM_DONE event handler.
 147   midi_header.release();
 148 }
 149
 150 }  // namespace
 151
 152 class MidiManagerWin::InDeviceInfo {
 153  public:
 154   ~InDeviceInfo() {
 155     Uninitialize();
 156   }
 157   void set_port_index(int index) {
 158     port_index_ = index;
 159   }
 160   int port_index() const {
 161     return port_index_;
 162   }
 163   bool device_to_be_closed() const {
 164     return device_to_be_closed_;
 165   }
 166   HMIDIIN midi_handle() const {
 167     return midi_handle_;
 168   }
 169
 170   static scoped_ptr<InDeviceInfo> Create(MidiManagerWin* manager,
 171                                          UINT device_id) {
 172     scoped_ptr<InDeviceInfo> obj(new InDeviceInfo(manager));
 173     if (!obj->Initialize(device_id))
 174       obj.reset();
 175     return obj.Pass();
 176   }
 177
 178  private:
 179   static const int kInvalidPortIndex = -1;
 180   static const size_t kBufferLength = 32 * 1024;
 181
 182   explicit InDeviceInfo(MidiManagerWin* manager)
 183       : manager_(manager),
 184         port_index_(kInvalidPortIndex),
 185         midi_handle_(NULL),
 186         started_(false),
 187         device_to_be_closed_(false) {
 188   }
 189
 190   bool Initialize(DWORD device_id) {
 191     Uninitialize();
 192     midi_header_ = CreateMIDIHDR(kBufferLength);
 193
 194     // Here we use |CALLBACK_FUNCTION| to subscribe MIM_DATA, MIM_LONGDATA, and
 195     // MIM_CLOSE events.
 196     // - MIM_DATA: This is the only way to get a short MIDI message with
 197     //     timestamp information.
 198     // - MIM_LONGDATA: This is the only way to get a long MIDI message with
 199     //     timestamp information.
 200     // - MIM_CLOSE: This event is sent when 1) midiInClose() is called, or 2)
 201     //     the MIDI device becomes unavailable for some reasons, e.g., the cable
 202     //     is disconnected. As for the former case, HMIDIOUT will be invalidated
 203     //     soon after the callback is finished. As for the later case, however,
 204     //     HMIDIOUT continues to be valid until midiInClose() is called.
 205     MMRESULT result = midiInOpen(&midi_handle_,
 206                                  device_id,
 207                                  reinterpret_cast<DWORD_PTR>(&HandleMessage),
 208                                  reinterpret_cast<DWORD_PTR>(this),
 209                                  CALLBACK_FUNCTION);
 210     if (result != MMSYSERR_NOERROR) {
 211       DLOG(ERROR) << "Failed to open output device. "
 212                   << " id: " << device_id
 213                   << " message: " << GetInErrorMessage(result);
 214       return false;
 215     }
 216     result = midiInPrepareHeader(
 217         midi_handle_, midi_header_.get(), sizeof(*midi_header_));
 218     if (result != MMSYSERR_NOERROR) {
 219       DLOG(ERROR) << "Failed to initialize input buffer: "
 220                   << GetInErrorMessage(result);
 221       return false;
 222     }
 223     result = midiInAddBuffer(
 224         midi_handle_, midi_header_.get(), sizeof(*midi_header_));
 225     if (result != MMSYSERR_NOERROR) {
 226       DLOG(ERROR) << "Failed to attach input buffer: "
 227                   << GetInErrorMessage(result);
 228       return false;
 229     }
 230     result = midiInStart(midi_handle_);
 231     if (result != MMSYSERR_NOERROR) {
 232       DLOG(ERROR) << "Failed to start input port: "
 233                   << GetInErrorMessage(result);
 234       return false;
 235     }
 236     started_ = true;
 237     start_time_ = base::TimeTicks::Now();
 238     return true;
 239   }
 240
 241   void Uninitialize() {
 242     MMRESULT result = MMSYSERR_NOERROR;
 243     if (midi_handle_ && started_) {
 244       result = midiInStop(midi_handle_);
 245       DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 246           << "Failed to stop input port: " << GetInErrorMessage(result);
 247       started_ = false;
 248       start_time_ = base::TimeTicks();
 249     }
 250     if (midi_handle_) {
 251       // midiInReset flushes pending messages. We ignore these messages.
 252       device_to_be_closed_ = true;
 253       result = midiInReset(midi_handle_);
 254       DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 255           << "Failed to reset input port: " << GetInErrorMessage(result);
 256       result = midiInClose(midi_handle_);
 257       device_to_be_closed_ = false;
 258       DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 259           << "Failed to close input port: " << GetInErrorMessage(result);
 260       midi_header_.reset();
 261       midi_handle_ = NULL;
 262       port_index_ = kInvalidPortIndex;
 263     }
 264   }
 265
 266   static void CALLBACK HandleMessage(HMIDIIN midi_in_handle,
 267                                      UINT message,
 268                                      DWORD_PTR instance,
 269                                      DWORD_PTR param1,
 270                                      DWORD_PTR param2) {
 271     // This method can be called back on any thread depending on Windows
 272     // multimedia subsystem and underlying MIDI drivers.
 273     InDeviceInfo* self = reinterpret_cast<InDeviceInfo*>(instance);
 274     if (!self)
 275       return;
 276     if (self->midi_handle() != midi_in_handle)
 277       return;
 278
 279     switch (message) {
 280       case MIM_DATA:
 281         self->OnShortMessageReceived(static_cast<uint8>(param1 & 0xff),
 282                                      static_cast<uint8>((param1 >> 8) & 0xff),
 283                                      static_cast<uint8>((param1 >> 16) & 0xff),
 284                                      param2);
 285         return;
 286       case MIM_LONGDATA:
 287         self->OnLongMessageReceived(reinterpret_cast<MIDIHDR*>(param1),
 288                                     param2);
 289         return;
 290       case MIM_CLOSE:
 291         // TODO(yukawa): Implement crbug.com/279097.
 292         return;
 293     }
 294   }
 295
 296   void OnShortMessageReceived(uint8 status_byte,
 297                               uint8 first_data_byte,
 298                               uint8 second_data_byte,
 299                               DWORD elapsed_ms) {
 300     if (device_to_be_closed())
 301       return;
 302     const size_t len = GetMidiMessageLength(status_byte);
 303     if (len == 0 || port_index() == kInvalidPortIndex)
 304       return;
 305     const uint8 kData[] = { status_byte, first_data_byte, second_data_byte };
 306     DCHECK_LE(len, arraysize(kData));
 307     OnMessageReceived(kData, len, elapsed_ms);
 308   }
 309
 310   void OnLongMessageReceived(MIDIHDR* header, DWORD elapsed_ms) {
 311     if (header != midi_header_.get())
 312       return;
 313     MMRESULT result = MMSYSERR_NOERROR;
 314     if (device_to_be_closed()) {
 315       if (midi_header_ &&
 316           (midi_header_->dwFlags & MHDR_PREPARED) == MHDR_PREPARED) {
 317         result = midiInUnprepareHeader(
 318             midi_handle_, midi_header_.get(), sizeof(*midi_header_));
 319         DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 320             << "Failed to uninitialize input buffer: "
 321             << GetInErrorMessage(result);
 322       }
 323       return;
 324     }
 325     if (header->dwBytesRecorded > 0 && port_index() != kInvalidPortIndex) {
 326       OnMessageReceived(reinterpret_cast<const uint8*>(header->lpData),
 327                         header->dwBytesRecorded,
 328                         elapsed_ms);
 329     }
 330     result = midiInAddBuffer(midi_handle_, header, sizeof(*header));
 331     DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 332         << "Failed to attach input port: " << GetInErrorMessage(result);
 333   }
 334
 335   void OnMessageReceived(const uint8* data, size_t length, DWORD elapsed_ms) {
 336     // MIM_DATA/MIM_LONGDATA message treats the time when midiInStart() is
 337     // called as the origin of |elapsed_ms|.
 338     // http://msdn.microsoft.com/en-us/library/windows/desktop/dd757284.aspx
 339     // http://msdn.microsoft.com/en-us/library/windows/desktop/dd757286.aspx
 340     const base::TimeTicks event_time =
 341         start_time_ + base::TimeDelta::FromMilliseconds(elapsed_ms);
 342     manager_->ReceiveMidiData(port_index_, data, length, event_time);
 343   }
 344
 345   MidiManagerWin* manager_;
 346   int port_index_;
 347   HMIDIIN midi_handle_;
 348   ScopedMIDIHDR midi_header_;
 349   base::TimeTicks start_time_;
 350   bool started_;
 351   bool device_to_be_closed_;
 352   DISALLOW_COPY_AND_ASSIGN(InDeviceInfo);
 353 };
 354
 355 class MidiManagerWin::OutDeviceInfo {
 356  public:
 357   ~OutDeviceInfo() {
 358     Uninitialize();
 359   }
 360
 361   static scoped_ptr<OutDeviceInfo> Create(UINT device_id) {
 362     scoped_ptr<OutDeviceInfo> obj(new OutDeviceInfo);
 363     if (!obj->Initialize(device_id))
 364       obj.reset();
 365     return obj.Pass();
 366   }
 367
 368   HMIDIOUT midi_handle() const {
 369     return midi_handle_;
 370   }
 371
 372   void Quit() {
 373     quitting_ = true;
 374   }
 375
 376   void Send(const std::vector<uint8>& data) {
 377     // Check if the attached device is still available or not.
 378     if (!midi_handle_)
 379       return;
 380
 381     // Give up sending MIDI messages here if the device is already closed.
 382     // Note that this check is optional. Regardless of that we check |closed_|
 383     // or not, nothing harmful happens as long as |midi_handle_| is still valid.
 384     if (closed_)
 385       return;
 386
 387     // MIDI Running status must be filtered out.
 388     MidiMessageQueue message_queue(false);
 389     message_queue.Add(data);
 390     std::vector<uint8> message;
 391     while (!quitting_) {
 392       message_queue.Get(&message);
 393       if (message.empty())
 394         break;
 395       // SendShortMidiMessageInternal can send a MIDI message up to 3 bytes.
 396       if (message.size() <= 3)
 397         SendShortMidiMessageInternal(midi_handle_, message);
 398       else
 399         SendLongMidiMessageInternal(midi_handle_, message);
 400     }
 401   }
 402
 403  private:
 404   OutDeviceInfo()
 405       : midi_handle_(NULL),
 406         closed_(false),
 407         quitting_(false) {}
 408
 409   bool Initialize(DWORD device_id) {
 410     Uninitialize();
 411     // Here we use |CALLBACK_FUNCTION| to subscribe MOM_DONE and MOM_CLOSE
 412     // events.
 413     // - MOM_DONE: SendLongMidiMessageInternal() relies on this event to clean
 414     //     up the backing store where a long MIDI message is stored.
 415     // - MOM_CLOSE: This event is sent when 1) midiOutClose() is called, or 2)
 416     //     the MIDI device becomes unavailable for some reasons, e.g., the cable
 417     //     is disconnected. As for the former case, HMIDIOUT will be invalidated
 418     //     soon after the callback is finished. As for the later case, however,
 419     //     HMIDIOUT continues to be valid until midiOutClose() is called.
 420     MMRESULT result = midiOutOpen(&midi_handle_,
 421                                   device_id,
 422                                   reinterpret_cast<DWORD_PTR>(&HandleMessage),
 423                                   reinterpret_cast<DWORD_PTR>(this),
 424                                   CALLBACK_FUNCTION);
 425     if (result != MMSYSERR_NOERROR) {
 426       DLOG(ERROR) << "Failed to open output device. "
 427                   << " id: " << device_id
 428                   << " message: "<< GetOutErrorMessage(result);
 429       midi_handle_ = NULL;
 430       return false;
 431     }
 432     return true;
 433   }
 434
 435   void Uninitialize() {
 436     if (!midi_handle_)
 437       return;
 438
 439     MMRESULT result = midiOutReset(midi_handle_);
 440     DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 441         << "Failed to reset output port: " << GetOutErrorMessage(result);
 442     result = midiOutClose(midi_handle_);
 443     DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 444         << "Failed to close output port: " << GetOutErrorMessage(result);
 445     midi_handle_ = NULL;
 446     closed_ = true;
 447   }
 448
 449   static void CALLBACK HandleMessage(HMIDIOUT midi_out_handle,
 450                                      UINT message,
 451                                      DWORD_PTR instance,
 452                                      DWORD_PTR param1,
 453                                      DWORD_PTR param2) {
 454     // This method can be called back on any thread depending on Windows
 455     // multimedia subsystem and underlying MIDI drivers.
 456
 457     OutDeviceInfo* self = reinterpret_cast<OutDeviceInfo*>(instance);
 458     if (!self)
 459       return;
 460     if (self->midi_handle() != midi_out_handle)
 461       return;
 462     switch (message) {
 463       case MOM_DONE: {
 464         // Take ownership of the MIDIHDR object.
 465         ScopedMIDIHDR header(reinterpret_cast<MIDIHDR*>(param1));
 466         if (!header)
 467           return;
 468         MMRESULT result = midiOutUnprepareHeader(
 469             self->midi_handle(), header.get(), sizeof(*header));
 470         DLOG_IF(ERROR, result != MMSYSERR_NOERROR)
 471             << "Failed to uninitialize output buffer: "
 472             << GetOutErrorMessage(result);
 473         return;
 474       }
 475       case MOM_CLOSE:
 476         // No lock is required since this flag is just a hint to avoid
 477         // unnecessary API calls that will result in failure anyway.
 478         self->closed_ = true;
 479         // TODO(yukawa): Implement crbug.com/279097.
 480         return;
 481     }
 482   }
 483
 484   HMIDIOUT midi_handle_;
 485
 486   // True if the device is already closed.
 487   volatile bool closed_;
 488
 489   // True if the MidiManagerWin is trying to stop the sender thread.
 490   volatile bool quitting_;
 491
 492   DISALLOW_COPY_AND_ASSIGN(OutDeviceInfo);
 493 };
 494
 495 MidiManagerWin::MidiManagerWin()
 496     : send_thread_("MidiSendThread") {
 497 }
 498
 499 void MidiManagerWin::StartInitialization() {
 500   const UINT num_in_devices = midiInGetNumDevs();
 501   in_devices_.reserve(num_in_devices);
 502   int inport_index = 0;
 503   for (UINT device_id = 0; device_id < num_in_devices; ++device_id) {
 504     MIDIINCAPS caps = {};
 505     MMRESULT result = midiInGetDevCaps(device_id, &caps, sizeof(caps));
 506     if (result != MMSYSERR_NOERROR) {
 507       DLOG(ERROR) << "Failed to obtain input device info: "
 508                   << GetInErrorMessage(result);
 509       continue;
 510     }
 511     scoped_ptr<InDeviceInfo> in_device(InDeviceInfo::Create(this, device_id));
 512     if (!in_device)
 513       continue;
 514     MidiPortInfo info(
 515         base::IntToString(static_cast<int>(device_id)),
 516         "",
 517         base::WideToUTF8(caps.szPname),
 518         base::IntToString(static_cast<int>(caps.vDriverVersion)),
 519         MIDI_PORT_OPENED);
 520     AddInputPort(info);
 521     in_device->set_port_index(inport_index++);
 522     in_devices_.push_back(in_device.release());
 523   }
 524
 525   const UINT num_out_devices = midiOutGetNumDevs();
 526   out_devices_.reserve(num_out_devices);
 527   for (UINT device_id = 0; device_id < num_out_devices; ++device_id) {
 528     MIDIOUTCAPS caps = {};
 529     MMRESULT result = midiOutGetDevCaps(device_id, &caps, sizeof(caps));
 530     if (result != MMSYSERR_NOERROR) {
 531       DLOG(ERROR) << "Failed to obtain output device info: "
 532                   << GetOutErrorMessage(result);
 533       continue;
 534     }
 535     scoped_ptr<OutDeviceInfo> out_port(OutDeviceInfo::Create(device_id));
 536     if (!out_port)
 537       continue;
 538     MidiPortInfo info(
 539         base::IntToString(static_cast<int>(device_id)),
 540         "",
 541         base::WideToUTF8(caps.szPname),
 542         base::IntToString(static_cast<int>(caps.vDriverVersion)),
 543         MIDI_PORT_OPENED);
 544     AddOutputPort(info);
 545     out_devices_.push_back(out_port.release());
 546   }
 547
 548   CompleteInitialization(MIDI_OK);
 549 }
 550
 551 MidiManagerWin::~MidiManagerWin() {
 552   // Cleanup order is important. |send_thread_| must be stopped before
 553   // |out_devices_| is cleared.
 554   for (auto& device : out_devices_)
 555     device->Quit();
 556   send_thread_.Stop();
 557
 558   out_devices_.clear();
 559   in_devices_.clear();
 560 }
 561
 562 void MidiManagerWin::DispatchSendMidiData(MidiManagerClient* client,
 563                                           uint32 port_index,
 564                                           const std::vector<uint8>& data,
 565                                           double timestamp) {
 566   if (out_devices_.size() <= port_index)
 567     return;
 568
 569   base::TimeDelta delay;
 570   if (timestamp != 0.0) {
 571     base::TimeTicks time_to_send =
 572         base::TimeTicks() + base::TimeDelta::FromMicroseconds(
 573             timestamp * base::Time::kMicrosecondsPerSecond);
 574     delay = std::max(time_to_send - base::TimeTicks::Now(), base::TimeDelta());
 575   }
 576
 577   if (!send_thread_.IsRunning())
 578     send_thread_.Start();
 579
 580   OutDeviceInfo* out_port = out_devices_[port_index];
 581   send_thread_.message_loop()->PostDelayedTask(
 582       FROM_HERE,
 583       base::Bind(&OutDeviceInfo::Send, base::Unretained(out_port), data),
 584       delay);
 585
 586   // Call back AccumulateMidiBytesSent() on |send_thread_| to emulate the
 587   // behavior of MidiManagerMac::SendMidiData.
 588   // TODO(yukawa): Do this task in a platform-independent way if possible.
 589   // See crbug.com/325810.
 590   send_thread_.message_loop()->PostTask(
 591       FROM_HERE,
 592       base::Bind(&MidiManagerClient::AccumulateMidiBytesSent,
 593                  base::Unretained(client), data.size()));
 594 }
 595
 596 MidiManager* MidiManager::Create() {
 597   return new MidiManagerWin();
 598 }
 599
 600 }  // namespace media