Add thread safety to AudioManagerBase to protect access to the audio thread member variable.

media/audio/audio_output_proxy.cc

 // Copyright (c) 2011 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/audio/audio_output_proxy.h"
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_output_dispatcher.h"
 
 AudioOutputProxy::AudioOutputProxy(AudioOutputDispatcher* dispatcher)
     : dispatcher_(dispatcher),
       state_(kCreated),
       physical_stream_(NULL),
       volume_(1.0) {
-  DCHECK_EQ(MessageLoop::current(), dispatcher_->message_loop());
 }
 
 AudioOutputProxy::~AudioOutputProxy() {
-  DCHECK_EQ(MessageLoop::current(), dispatcher_->message_loop());
+  DCHECK(CalledOnValidThread());
   DCHECK(state_ == kCreated || state_ == kClosed);
   DCHECK(!physical_stream_);
 }
 
 bool AudioOutputProxy::Open() {
-  DCHECK_EQ(MessageLoop::current(), dispatcher_->message_loop());
+  DCHECK(CalledOnValidThread());
   DCHECK_EQ(state_, kCreated);
 
   if (!dispatcher_->StreamOpened()) {
     state_ = kError;
     return false;
   }
 
   state_ = kOpened;
   return true;
 }
 
 void AudioOutputProxy::Start(AudioSourceCallback* callback) {
-  DCHECK_EQ(MessageLoop::current(), dispatcher_->message_loop());
+  DCHECK(CalledOnValidThread());
   DCHECK(physical_stream_ == NULL);
   DCHECK_EQ(state_, kOpened);
 
   physical_stream_= dispatcher_->StreamStarted();
   if (!physical_stream_) {
     state_ = kError;
     callback->OnError(this, 0);
     return;
   }
 
   physical_stream_->SetVolume(volume_);
   physical_stream_->Start(callback);
   state_ = kPlaying;
 }
 
 void AudioOutputProxy::Stop() {
-  DCHECK_EQ(MessageLoop::current(), dispatcher_->message_loop());
+  DCHECK(CalledOnValidThread());
   if (state_ != kPlaying)
     return;
 
   DCHECK(physical_stream_);
   physical_stream_->Stop();
   dispatcher_->StreamStopped(physical_stream_);
   physical_stream_ = NULL;
   state_ = kOpened;
 }
 
 void AudioOutputProxy::SetVolume(double volume) {
-  DCHECK_EQ(MessageLoop::current(), dispatcher_->message_loop());
+  DCHECK(CalledOnValidThread());
   volume_ = volume;
   if (physical_stream_) {
     physical_stream_->SetVolume(volume);
   }
 }
 
 void AudioOutputProxy::GetVolume(double* volume) {
-  DCHECK_EQ(MessageLoop::current(), dispatcher_->message_loop());
+  DCHECK(CalledOnValidThread());
   *volume = volume_;
 }
 
 void AudioOutputProxy::Close() {
-  DCHECK_EQ(MessageLoop::current(), dispatcher_->message_loop());
+  DCHECK(CalledOnValidThread());
   DCHECK(state_ == kCreated || state_ == kError || state_ == kOpened);
   DCHECK(!physical_stream_);
 
   if (state_ != kCreated)
     dispatcher_->StreamClosed();
 
   state_ = kClosed;
 
   // Delete the object now like is done in the Close() implementation of
   // physical stream objects.  If we delete the object via DeleteSoon, we
   // unnecessarily complicate the Shutdown procedure of the
   // dispatcher+audio manager.
   delete this;
 }