Implements AudioMessageFilter as member in RenderThread

content/renderer/media/audio_device.cc

Index: content/renderer/media/audio_device.cc
===================================================================
--- content/renderer/media/audio_device.cc	(revision 88939)
+++ content/renderer/media/audio_device.cc	(working copy)
@@ -9,42 +9,11 @@
 #include "content/common/audio_messages.h"
 #include "content/common/child_process.h"
 #include "content/common/view_messages.h"
+#include "content/renderer/media/audio_message_filter.h"
+#include "content/renderer/media/audio_message_filter_creator.h"
 #include "content/renderer/render_thread.h"
 #include "media/audio/audio_util.h"
 
-scoped_refptr<AudioMessageFilter> AudioDevice::filter_;
-
-namespace {
-
-// AudioMessageFilterCreator is intended to be used as a singleton so we can
-// get access to a shared AudioMessageFilter.
-// Example usage:
-//   AudioMessageFilter* filter = AudioMessageFilterCreator::SharedFilter();
-
-class AudioMessageFilterCreator {
- public:
-  AudioMessageFilterCreator() {
-    int routing_id;
-    RenderThread::current()->Send(
-        new ViewHostMsg_GenerateRoutingID(&routing_id));
-    filter_ = new AudioMessageFilter(routing_id);
-    RenderThread::current()->AddFilter(filter_);
-  }
-
-  static AudioMessageFilter* SharedFilter() {
-    return GetInstance()->filter_.get();
-  }
-
-  static AudioMessageFilterCreator* GetInstance() {
-    return Singleton<AudioMessageFilterCreator>::get();
-  }
-
- private:
-  scoped_refptr<AudioMessageFilter> filter_;
-};
-
-}  // namespace
-
 AudioDevice::AudioDevice(size_t buffer_size,
                          int channels,
                          double sample_rate,
@@ -56,14 +25,15 @@
       callback_(callback),
       audio_delay_milliseconds_(0),
       volume_(1.0),
-      stream_id_(0) {
+      stream_id_(0),
+      filter_(AudioMessageFilterCreator::SharedFilter()),
+      io_loop_(filter_->message_loop()) {
+  DCHECK(io_loop_);
   audio_data_.reserve(channels);
   for (int i = 0; i < channels; ++i) {
     float* channel_data = new float[buffer_size];
     audio_data_.push_back(channel_data);
   }
-  // Lazily create the message filter and share across AudioDevice instances.
-  filter_ = AudioMessageFilterCreator::SharedFilter();
 }
 
 AudioDevice::~AudioDevice() {
@@ -87,18 +57,9 @@
   params.bits_per_sample = bits_per_sample_;
   params.samples_per_packet = buffer_size_;
 
-  // Ensure that the initialization task is posted on the I/O thread by
-  // accessing the I/O message loop directly. This approach avoids a race
-  // condition which could exist if the message loop of the filter was
-  // used instead.
-  DCHECK(ChildProcess::current()) << "Must be in the renderer";
-  MessageLoop* message_loop = ChildProcess::current()->io_message_loop();
-  if (!message_loop)
-    return false;
+  io_loop_->PostTask(FROM_HERE,
+      NewRunnableMethod(this, &AudioDevice::InitializeTask, params));
 
-  message_loop->PostTask(FROM_HERE,
-      NewRunnableMethod(this, &AudioDevice::InitializeOnIOThread, params));
-
   return true;
 }
 
@@ -106,8 +67,8 @@
   if (!stream_id_)
     return false;
 
-  filter_->message_loop()->PostTask(FROM_HERE,
-      NewRunnableMethod(this, &AudioDevice::ShutDownOnIOThread));
+  io_loop_->PostTask(FROM_HERE,
+      NewRunnableMethod(this, &AudioDevice::ShutDownTask));
 
   if (audio_thread_.get()) {
     socket_->Close();
@@ -124,8 +85,8 @@
   if (volume < 0 || volume > 1.0)
     return false;
 
-  filter_->message_loop()->PostTask(FROM_HERE,
-      NewRunnableMethod(this, &AudioDevice::SetVolumeOnIOThread, volume));
+  io_loop_->PostTask(FROM_HERE,
+      NewRunnableMethod(this, &AudioDevice::SetVolumeTask, volume));
 
   volume_ = volume;
 
@@ -142,27 +103,31 @@
   return true;
 }
 
-void AudioDevice::InitializeOnIOThread(const AudioParameters& params) {
+void AudioDevice::InitializeTask(const AudioParameters& params) {
+  DCHECK(MessageLoop::current() == io_loop_);
   stream_id_ = filter_->AddDelegate(this);
   filter_->Send(new AudioHostMsg_CreateStream(0, stream_id_, params, true));
 }
 
-void AudioDevice::StartOnIOThread() {
+void AudioDevice::StartTask() {
+  DCHECK(MessageLoop::current() == io_loop_);
   if (stream_id_)
     filter_->Send(new AudioHostMsg_PlayStream(0, stream_id_));
 }
 
-void AudioDevice::ShutDownOnIOThread() {
+void AudioDevice::ShutDownTask() {
+  DCHECK(MessageLoop::current() == io_loop_);
   // Make sure we don't call shutdown more than once.
   if (!stream_id_)
     return;
 
-  filter_->Send(new AudioHostMsg_CloseStream(0, stream_id_));
   filter_->RemoveDelegate(stream_id_);
+  filter_->Send(new AudioHostMsg_CloseStream(0, stream_id_));
   stream_id_ = 0;
 }
 
-void AudioDevice::SetVolumeOnIOThread(double volume) {
+void AudioDevice::SetVolumeTask(double volume) {
+  DCHECK(MessageLoop::current() == io_loop_);
   if (stream_id_)
     filter_->Send(new AudioHostMsg_SetVolume(0, stream_id_, volume));
 }
@@ -189,6 +154,7 @@
     base::SharedMemoryHandle handle,
     base::SyncSocket::Handle socket_handle,
     uint32 length) {
+  DCHECK(MessageLoop::current() == io_loop_);
 #if defined(OS_WIN)
   DCHECK(handle);
   DCHECK(socket_handle);
@@ -211,10 +177,8 @@
       new base::DelegateSimpleThread(this, "renderer_audio_thread"));
   audio_thread_->Start();
 
-  if (filter_) {
-    filter_->message_loop()->PostTask(FROM_HERE,
-        NewRunnableMethod(this, &AudioDevice::StartOnIOThread));
-  }
+  io_loop_->PostTask(FROM_HERE,
+      NewRunnableMethod(this, &AudioDevice::StartTask));
 }
 
 void AudioDevice::OnVolume(double volume) {