Add Mac OS X synchronized audio I/O back-end

media/base/audio_bus.cc

Index: media/base/audio_bus.cc
===================================================================
--- media/base/audio_bus.cc	(revision 157152)
+++ media/base/audio_bus.cc	(working copy)
@@ -105,7 +105,8 @@
 }
 
 AudioBus::AudioBus(int channels, int frames)
-    : frames_(frames) {
+    : frames_(frames),
+      can_set_channel_data_(false) {
   ValidateConfig(channels, frames_);
 
   int aligned_frames = 0;
@@ -118,7 +119,8 @@
 }
 
 AudioBus::AudioBus(int channels, int frames, float* data)
-    : frames_(frames) {
+    : frames_(frames),
+      can_set_channel_data_(false) {
   ValidateConfig(channels, frames_);
 
   int aligned_frames = 0;
@@ -129,7 +131,8 @@
 
 AudioBus::AudioBus(int frames, const std::vector<float*>& channel_data)
     : channel_data_(channel_data),
-      frames_(frames) {
+      frames_(frames),
+      can_set_channel_data_(false) {
   ValidateConfig(channel_data_.size(), frames_);
 
   // Sanity check wrapped vector for alignment and channel count.
@@ -137,6 +140,14 @@
     DCHECK(IsAligned(channel_data_[i]));
 }
 
+AudioBus::AudioBus(int channels)
+    : channel_data_(channels),
+      frames_(0),
+      can_set_channel_data_(true) {
+  for (size_t i = 0; i < channel_data_.size(); ++i)
+    channel_data_[i] = NULL;
+}
+
 AudioBus::~AudioBus() {}
 
 scoped_ptr<AudioBus> AudioBus::Create(int channels, int frames) {
@@ -148,6 +159,10 @@
       params.channels(), params.frames_per_buffer()));
 }
 
+scoped_ptr<AudioBus> AudioBus::CreateWrapper(int channels) {
+  return scoped_ptr<AudioBus>(new AudioBus(channels));
+}
+
 scoped_ptr<AudioBus> AudioBus::WrapVector(
     int frames, const std::vector<float*>& channel_data) {
   return scoped_ptr<AudioBus>(new AudioBus(frames, channel_data));
@@ -170,6 +185,19 @@
       static_cast<float*>(data)));
 }
 
+void AudioBus::SetChannelData(int channel, float* data) {
+  CHECK(can_set_channel_data_);
+  CHECK_GE(channel, 0);
+  CHECK_LT(static_cast<size_t>(channel), channel_data_.size());
+  DCHECK(IsAligned(data));
+  channel_data_[channel] = data;
+}
+
+void AudioBus::set_frames(int frames) {
+  CHECK(can_set_channel_data_);
+  frames_ = frames;
+}
+
 void AudioBus::ZeroFramesPartial(int start_frame, int frames) {
   CheckOverflow(start_frame, frames, frames_);