Fix some threading issues and some refactoring in AudioRendererHost

1. AudioRendererHost should not wait on IO thread.
   Calling AudioOutputStream::Start requests some
   audio packets by calling IPCAudioSource::OnMoreData,
   resulting in a deadlock. I implemented a prefetching
   logic to solve this problem, source has to know
   how many internal buffers the implementation of
   AudioOutputStream is using and prepare the
   same amount of packets before calling
   AudioOutputStream::Start.
2. When IPCAudioSource::OnMoreData is waiting for
   packet to arrive, calling AudioOutputStream::Stop
   will result in a deadlock since it expects
   OnMoreData to return. Should wake up all waiting
   threads before calling AudioOutputStream::Stop.
3. Did some refactoring and move the message handlers
   completely into AudioRendererHost, it was clumsy
   to call to AudioRendererHost from ResourceMessageFilter.
   Also moved all logics of using shared memory for
   packet passing, prefetching to IPCAudioSource.
   AudioRendererHost is now merely a container that
   manages and delegates calls to IPCAudioSource. This
   refactoring is helpful because the next step is to
   implement standalone IPC channel for audio.
Review URL: http://codereview.chromium.org/57023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@13288 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 6 insertions, 2 deletions

diff --git a/media/audio/mac/audio_output_mac.cc b/media/audio/mac/audio_output_mac.cc
index 3866a56..da6772f 100644
--- a/media/audio/mac/audio_output_mac.cc
+++ b/media/audio/mac/audio_output_mac.cc
@@ -9,7 +9,7 @@
 
 PCMQueueOutAudioOutputStream::PCMQueueOutAudioOutputStream(
     AudioManagerMac* manager, int channels, int sampling_rate,
-    char bits_per_sample) 
+    char bits_per_sample)
         : format_(),
           audio_queue_(NULL),
           buffer_(),
@@ -91,7 +91,7 @@ void PCMQueueOutAudioOutputStream::Close() {
 }
 
 void PCMQueueOutAudioOutputStream::Stop() {
-  // TODO(cpu): Implement.  
+  // TODO(cpu): Implement.
 }
 
 void PCMQueueOutAudioOutputStream::SetVolume(double left_level,
@@ -104,6 +104,10 @@ void PCMQueueOutAudioOutputStream::GetVolume(double* left_level,
   // TODO(cpu): Implement.
 }
 
+size_t PCMQueueOutAudioOutputStream::GetNumBuffers() {
+  return kNumBuffers;
+}
+
 void PCMQueueOutAudioOutputStream::RenderCallback(void* p_this,
                                                   AudioQueueRef queue,
                                                   AudioQueueBufferRef buffer) {