Refactoring to share MockAudioOutputStream implementations across 3 platforms

media/audio/mac/audio_manager_mac.cc

 // Copyright (c) 2009 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 <CoreAudio/AudioHardware.h>
 
 #include "base/at_exit.h"
+#include "media/audio/fake_audio_output_stream.h"
 #include "media/audio/mac/audio_manager_mac.h"
 #include "media/audio/mac/audio_output_mac.h"
 
 bool AudioManagerMac::HasAudioDevices() {
   AudioDeviceID output_device_id = 0;
   size_t size = sizeof(output_device_id);
   OSStatus err = AudioHardwareGetProperty(
       kAudioHardwarePropertyDefaultOutputDevice, &size, &output_device_id);
   return ((err == noErr) && (output_device_id > 0));
 }
 
 AudioOutputStream* AudioManagerMac::MakeAudioStream(Format format, int channels,
                                                     int sample_rate,
                                                     char bits_per_sample) {
-  // TODO(cpu): add mock format.
-  if (format != AUDIO_PCM_LINEAR)
+  if (format == AUDIO_MOCK)
+    return FakeAudioOutputStream::MakeFakeStream();
+  else if (format != AUDIO_PCM_LINEAR)
     return NULL;
   return new PCMQueueOutAudioOutputStream(this, channels, sample_rate,
                                           bits_per_sample);
 }
 
 void AudioManagerMac::MuteAll() {
   // TODO(cpu): implement.
 }
 
 void AudioManagerMac::UnMuteAll() {
   // TODO(cpu): implement.
 }
 
-const void* AudioManagerMac::GetLastMockBuffer() {
-  // TODO(cpu): implement.
-  return NULL;
-}
-
 // Called by the stream when it has been released by calling Close().
 void AudioManagerMac::ReleaseStream(PCMQueueOutAudioOutputStream* stream) {
   delete stream;
 }
 
 namespace {
-  AudioManagerMac* g_audio_manager = NULL;
-  
+
+AudioManagerMac* g_audio_manager = NULL;
+
 }  // namespace.
 
 void DestroyAudioManagerMac(void* param) {
   delete g_audio_manager;
   g_audio_manager = NULL;
 }
 
 // By convention, the AudioManager is not thread safe.
 AudioManager* AudioManager::GetAudioManager() {
   if (!g_audio_manager) {
     g_audio_manager = new AudioManagerMac();
     base::AtExitManager::RegisterCallback(&DestroyAudioManagerMac, NULL);
   }
   return g_audio_manager;
 }