Allow audio system to handle synchronized low-latency audio I/O

media/audio/audio_output_controller.cc

 // Copyright (c) 2012 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 "media/audio/audio_output_controller.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
 #include "base/synchronization/waitable_event.h"
@@ skipping 265 matching lines @@
       return;
   }
 }
 
 void AudioOutputController::DoReportError(int code) {
   DCHECK(message_loop_->BelongsToCurrentThread());
   if (state_ != kClosed)
     handler_->OnError(this, code);
 }
 
-int AudioOutputController::OnMoreData(AudioBus* audio_bus,
+int AudioOutputController::OnMoreData(AudioBus* dest,
                                       AudioBuffersState buffers_state) {
-  TRACE_EVENT0("audio", "AudioOutputController::OnMoreData");
+  return OnMoreIOData(NULL, dest, buffers_state);
+}
+
+int AudioOutputController::OnMoreIOData(AudioBus* source,
+                                        AudioBus* dest,
+                                        AudioBuffersState buffers_state) {
+  TRACE_EVENT0("audio", "AudioOutputController::OnMoreIOData");
 
   {
     // Check state and do nothing if we are not playing.
     // We are on the hardware audio thread, so lock is needed.
     base::AutoLock auto_lock(lock_);
     if (state_ != kPlaying) {
       return 0;
     }
   }
-  int frames = sync_reader_->Read(audio_bus);
+
+  int frames = sync_reader_->Read(source, dest);
   sync_reader_->UpdatePendingBytes(
       buffers_state.total_bytes() + frames * params_.GetBytesPerFrame());
   return frames;
 }
 
 void AudioOutputController::WaitTillDataReady() {
   if (!sync_reader_->DataReady()) {
     // In the different place we use different mechanism to poll, get max
     // polling delay from constants used there.
     const base::TimeDelta kMaxPollingDelay = TimeDelta::FromMilliseconds(
@@ skipping 22 matching lines @@
     stream_ = NULL;
     weak_this_.InvalidateWeakPtrs();
   }
 
   // Should be last in the method, do not touch "this" from here on.
   if (done != NULL)
     done->Signal();
 }
 
 }  // namespace media