Change audio renderer to communicate with host using low latency codepath.

content/renderer/media/audio_renderer_impl.h

 // 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.
 //
 // Audio rendering unit utilizing audio output stream provided by browser
 // process through IPC.
 //
 // Relationship of classes.
 //
 //    AudioRendererHost                AudioRendererImpl
@@ skipping 25 matching lines @@
 
 #ifndef CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
 #define CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
 #pragma once
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/shared_memory.h"
 #include "base/synchronization/lock.h"
+#include "base/threading/simple_thread.h"
 #include "content/renderer/media/audio_message_filter.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_manager.h"
 #include "media/base/filters.h"
 #include "media/filters/audio_renderer_base.h"
 
 class AudioMessageFilter;
 
 class AudioRendererImpl : public media::AudioRendererBase,
                           public AudioMessageFilter::Delegate,
+                          public base::DelegateSimpleThread::Delegate,
                           public MessageLoop::DestructionObserver {
  public:
   // Methods called on Render thread ------------------------------------------
   explicit AudioRendererImpl(AudioMessageFilter* filter);
   virtual ~AudioRendererImpl();
 
   // Methods called on IO thread ----------------------------------------------
   // AudioMessageFilter::Delegate methods, called by AudioMessageFilter.
   virtual void OnRequestPacket(AudioBuffersState buffers_state);
   virtual void OnStateChanged(AudioStreamState state);
@@ skipping 16 matching lines @@
  protected:
   // Methods called on audio renderer thread ----------------------------------
   // These methods are called from AudioRendererBase.
   virtual bool OnInitialize(const media::AudioDecoderConfig& config);
   virtual void OnStop();
 
   // Called when the decoder completes a Read().
   virtual void ConsumeAudioSamples(scoped_refptr<media::Buffer> buffer_in);
 
  private:
+  // We are using either low- or high-latency code path.
+  enum LatencyType {
+    kUninitializedLatency = 0,
+    kLowLatency,
+    kHighLatency
+  };
+  static LatencyType latency_type_;
+
   // For access to constructor and IO thread methods.
   friend class AudioRendererImplTest;
   FRIEND_TEST_ALL_PREFIXES(AudioRendererImplTest, Stop);
   FRIEND_TEST_ALL_PREFIXES(AudioRendererImplTest,
                            DestroyedMessageLoop_ConsumeAudioSamples);
   // Helper methods.
   // Convert number of bytes to duration of time using information about the
   // number of channels, sample rate and sample bits.
   base::TimeDelta ConvertToDuration(int bytes);
 
   // Methods call on IO thread ------------------------------------------------
   // The following methods are tasks posted on the IO thread that needs to
   // be executed on that thread. They interact with AudioMessageFilter and
   // sends IPC messages on that thread.
   void CreateStreamTask(const AudioParameters& params);
   void PlayTask();
   void PauseTask();
   void SeekTask();
   void SetVolumeTask(double volume);
   void NotifyPacketReadyTask();
   void DestroyTask();
 
   // Called on IO thread when message loop is dying.
   virtual void WillDestroyCurrentMessageLoop();
 
+  // DelegateSimpleThread::Delegate implementation.
+  virtual void Run();
+
+  // (Re-)starts playback.
+  void NotifyDataAvailableIfNecessary();
+
+  // Creates socket. Virtual so tests can override.
+  virtual void CreateSocket(base::SyncSocket::Handle socket_handle);
+
+  // Launching audio thread. Virtual so tests can override.
+  virtual void CreateAudioThread();
+
+  // Accessors used by tests.
+  LatencyType latency_type() {
+    return latency_type_;
+  }
+
+  // Should be called before any class instance is created.
+  static void set_latency_type(LatencyType latency_type);
+
   // Used to calculate audio delay given bytes.
   uint32 bytes_per_second_;
 
   scoped_refptr<AudioMessageFilter> filter_;
 
   // ID of the stream created in the browser process.
   int32 stream_id_;
 
   // Memory shared by the browser process for audio buffer.
   scoped_ptr<base::SharedMemory> shared_memory_;
   uint32 shared_memory_size_;
 
+  // Low latency IPC stuff.
+  scoped_ptr<base::SyncSocket> socket_;
+
+  // That thread waits for audio input.
+  scoped_ptr<base::DelegateSimpleThread> audio_thread_;
+
   // Message loop for the IO thread.
   MessageLoop* io_loop_;
 
   // Protects:
   // - |stopped_|
   // - |pending_request_|
   // - |request_buffers_state_|
   base::Lock lock_;
 
   // A flag that indicates this filter is called to stop.
   bool stopped_;
 
   // A flag that indicates an outstanding packet request.
   bool pending_request_;
 
   // State of the audio buffers at time of the last request.
   AudioBuffersState request_buffers_state_;
 
   // State variables for prerolling.
   bool prerolling_;
 
   // Remaining bytes for prerolling to complete.
   uint32 preroll_bytes_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_