Introduce media::AudioPushFifo and a couple of use cases (and clean-ups).

chrome/renderer/media/cast_receiver_audio_valve.h

 // Copyright 2015 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.
 
 #ifndef CHROME_RENDERER_MEDIA_CAST_RECEIVER_AUDIO_VALVE_H_
 #define CHROME_RENDERER_MEDIA_CAST_RECEIVER_AUDIO_VALVE_H_
 
 #include "base/synchronization/lock.h"
+#include "base/time/time.h"
 #include "media/base/audio_capturer_source.h"
+#include "media/base/audio_push_fifo.h"
 
 namespace media {
 class AudioBus;
 }
 
-// Forwards calls to |cb| until Stop is called.
+// Forwards calls to |cb| until Stop is called.  If the client requested a
+// different buffer size than that provided by the Cast Receiver, AudioPushFifo
+// is used to rectify that.
+//
 // Thread-safe.
 // All functions may block depending on contention.
 class CastReceiverAudioValve :
-    public media::AudioCapturerSource::CaptureCallback,
     public base::RefCountedThreadSafe<CastReceiverAudioValve> {
  public:
-  explicit CastReceiverAudioValve(
-      media::AudioCapturerSource::CaptureCallback* cb);
+  CastReceiverAudioValve(const media::AudioParameters& params,
+                         media::AudioCapturerSource::CaptureCallback* cb);
 
-  // AudioCapturerSource::CaptureCallback implementation.
-  void Capture(const media::AudioBus* audio_source,
-               int audio_delay_milliseconds,
-               double volume,
-               bool key_pressed) override;
-  void OnCaptureError(const std::string& message) override;
+  // Called on an unknown thread to provide more decoded audio data from the
+  // Cast Receiver.
+  void DeliverDecodedAudio(const media::AudioBus* audio_bus,
+                           base::TimeTicks playout_time);
 
   // When this returns, no more calls will be forwarded to |cb|.
   void Stop();
 
  private:
   friend class base::RefCountedThreadSafe<CastReceiverAudioValve>;
-  ~CastReceiverAudioValve() override;
+
+  ~CastReceiverAudioValve();
+
+  // Called by AudioPushFifo zero or more times during the call to Capture().
+  // Delivers audio data in the required buffer size to |cb_|.
+  void DeliverRebufferedAudio(const media::AudioBus& audio_bus,
+                              int frame_offset);
+
   media::AudioCapturerSource::CaptureCallback* cb_;
   base::Lock lock_;
+
+  media::AudioPushFifo fifo_;
+  const int sample_rate_;
+
+  // Used to pass the current playout time between DeliverDecodedAudio() and
+  // DeviliverRebufferedAudio().
+  base::TimeTicks current_playout_time_;
 };
 
 #endif  // CHROME_RENDERER_MEDIA_CAST_RECEIVER_AUDIO_VALVE_H_