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

media/audio/simple_sources.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.
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 #include <cmath>
 
 #include "media/audio/simple_sources.h"
 
 #include <algorithm>
@@ skipping 28 matching lines @@
       std::min(audio_bus->frames(), cap_ - time_state_) : audio_bus->frames();
   for (int i = 0; i < max_frames; ++i)
     audio_bus->channel(0)[i] = sin(2.0 * M_PI * f_ * time_state_++);
   for (int i = 1; i < audio_bus->channels(); ++i) {
     memcpy(audio_bus->channel(i), audio_bus->channel(0),
            max_frames * sizeof(*audio_bus->channel(i)));
   }
   return max_frames;
 }
 
+int SineWaveAudioSource::OnMoreIOData(AudioBus* source,
+                                      AudioBus* dest,
+                                      AudioBuffersState audio_buffers) {
+  NOTREACHED();
+  return 0;
+}
+
 void SineWaveAudioSource::OnError(AudioOutputStream* stream, int code) {
   NOTREACHED();
 }
 
 void SineWaveAudioSource::CapSamples(int cap) {
   base::AutoLock auto_lock(time_lock_);
   DCHECK_GT(cap, 0);
   cap_ = cap;
 }
 
 void SineWaveAudioSource::Reset() {
   base::AutoLock auto_lock(time_lock_);
   time_state_ = 0;
 }
 
 }  // namespace media