Web MIDI: fix multi-threading problem around message buffer handling

media/midi/midi_manager.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/midi/midi_manager.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
+#include "base/message_loop/message_loop.h"
 #include "base/threading/thread.h"
 
 namespace media {
 
 #if !defined(OS_MACOSX)
 // TODO(crogers): implement MIDIManager for other platforms.
 MIDIManager* MIDIManager::Create() {
   return NULL;
 }
 #endif
@@ skipping 36 matching lines @@
     int port_index,
     const uint8* data,
     size_t length,
     double timestamp) {
   base::AutoLock auto_lock(clients_lock_);
 
   for (ClientList::iterator i = clients_.begin(); i != clients_.end(); ++i)
     (*i)->ReceiveMIDIData(port_index, data, length, timestamp);
 }
 
+bool MIDIManager::CurrentlyOnMIDISendThread() {
+  return send_thread_->message_loop() == base::MessageLoop::current();
+}
+
 void MIDIManager::DispatchSendMIDIData(MIDIManagerClient* client,
-                                       int port_index,
-                                       const uint8* data,
-                                       size_t length,
+                                       unsigned int port_index,
+                                       const std::vector<uint8>& data,
                                        double timestamp) {
   // Lazily create the thread when first needed.
   if (!send_thread_) {
     send_thread_.reset(new base::Thread("MIDISendThread"));
     send_thread_->Start();
     send_message_loop_ = send_thread_->message_loop_proxy();
   }
 
   send_message_loop_->PostTask(
      FROM_HERE,
      base::Bind(&MIDIManager::SendMIDIData, base::Unretained(this),
-         client, port_index, data, length, timestamp));

[Takashi Toyoshima, 2013/08/21 13:48:22]

raw buffer could not be passed to another thread correctly.

+         client, port_index, data, timestamp));

[scherkus (not reviewing), 2013/08/21 17:46:29]

do you know how large |data| can typically be?

are we talking bytes, kilobytes, megabytes?

[Takashi Toyoshima, 2013/08/22 05:47:45]

Typically, it's just 3 Bytes.

 }
 
 }  // namespace media