Switch OnMoreData() to use AudioBus.

media/audio/mac/audio_low_latency_output_mac.cc

Index: media/audio/mac/audio_low_latency_output_mac.cc
diff --git a/media/audio/mac/audio_low_latency_output_mac.cc b/media/audio/mac/audio_low_latency_output_mac.cc
index d9127f8d2824b1c7040d10d71c8c83d10b49fb49..b9248dc25467ed52249340cda87c79d40240151f 100644
--- a/media/audio/mac/audio_low_latency_output_mac.cc
+++ b/media/audio/mac/audio_low_latency_output_mac.cc
@@ -53,7 +53,8 @@ AUAudioOutputStream::AUAudioOutputStream(
       output_device_id_(kAudioObjectUnknown),
       volume_(1),
       hardware_latency_frames_(0),
-      stopped_(false) {
+      stopped_(false),
+      audio_bus_(AudioBus::Create(params)) {
   // We must have a manager.
   DCHECK(manager_);
   // A frame is one sample across all channels. In interleaved audio the per
@@ -226,11 +227,19 @@ OSStatus AUAudioOutputStream::Render(UInt32 number_of_frames,
   uint8* audio_data = reinterpret_cast<uint8*>(buffer.mData);
   uint32 hardware_pending_bytes = static_cast<uint32>
       ((playout_latency_frames + 0.5) * format_.mBytesPerFrame);
-  uint32 filled = source_->OnMoreData(
-      audio_data, buffer.mDataByteSize,
-      AudioBuffersState(0, hardware_pending_bytes));
+
+  DCHECK_EQ(number_of_frames, static_cast<UInt32>(audio_bus_->frames()));
+  int frames_filled = source_->OnMoreData(
+      audio_bus_.get(), AudioBuffersState(0, hardware_pending_bytes));
+  // Note: If this ever changes to output raw float the data must be clipped and
+  // sanitized since it may come from an untrusted source such as NaCl.
+  audio_bus_->ToInterleaved(
+      frames_filled, format_.mBitsPerChannel / 8, audio_data);
+  uint32 filled = frames_filled * format_.mBytesPerFrame;
 
   // Handle channel order for 5.1 audio.
+  // TODO(dalecurtis): Channel downmixing, upmixing, should be done in mixer;
+  // volume adjust should use SSE optimized vector_fmul() prior to interleave.
   if (format_.mChannelsPerFrame == 6) {
     if (format_.mBitsPerChannel == 8) {
       SwizzleCoreAudioLayout5_1(reinterpret_cast<uint8*>(audio_data), filled);