Replace AudioDecoder::ProduceAudioSamples/ConsumeAudioSamples with read callbacks.

media/filters/audio_renderer_base.h

 // Copyright (c) 2011 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.
 
 // AudioRendererBase takes care of the tricky queuing work and provides simple
 // methods for subclasses to peek and poke at audio data.  In addition to
 // AudioRenderer interface methods this classes doesn't implement, subclasses
 // must also implement the following methods:
 //   OnInitialized
 //   OnStop
@@ skipping 39 matching lines @@
   // Subclasses should return true if they were able to initialize, false
   // otherwise.
   virtual bool OnInitialize(int bits_per_channel,
                             ChannelLayout channel_layout,
                             int sample_rate) = 0;
 
   // Called by Stop().  Subclasses should perform any necessary cleanup during
   // this time, such as stopping any running threads.
   virtual void OnStop() = 0;
 
-  // Called when a AudioDecoder completes decoding and decrements
-  // |pending_reads_|.
-  virtual void ConsumeAudioSamples(scoped_refptr<Buffer> buffer_in);
+  // Callback from the audio decoder delivering decoded audio samples.
+  void DecodedAudioReady(scoped_refptr<Buffer> buffer);
 
   // Fills the given buffer with audio data by delegating to its |algorithm_|.
   // FillBuffer() also takes care of updating the clock. Returns the number of
   // bytes copied into |dest|, which may be less than or equal to |len|.
   //
   // If this method is returns less bytes than |len| (including zero), it could
   // be a sign that the pipeline is stalled or unable to stream the data fast
   // enough.  In such scenarios, the callee should zero out unused portions
   // of their buffer to playback silence.
   //
@@ skipping 12 matching lines @@
   uint32 FillBuffer(uint8* dest,
                     uint32 len,
                     const base::TimeDelta& playback_delay,
                     bool buffers_empty);
 
   // Get/Set the playback rate of |algorithm_|.
   virtual void SetPlaybackRate(float playback_rate) OVERRIDE;
   virtual float GetPlaybackRate();
 
  private:
+  friend class AudioRendererBaseTest;
+
   // Helper method that schedules an asynchronous read from the decoder and
   // increments |pending_reads_|.
   //
   // Safe to call from any thread.
   void ScheduleRead_Locked();
 
   // Audio decoder.
   scoped_refptr<AudioDecoder> decoder_;
 
   // Algorithm for scaling audio.
   scoped_ptr<AudioRendererAlgorithmBase> algorithm_;
 
   base::Lock lock_;
 
   // Simple state tracking variable.
   enum State {
     kUninitialized,
     kPaused,
     kSeeking,
     kPlaying,
     kStopped,
     kError,
     kUnderflow,
     kRebuffering,
   };
   State state_;
 
+  // Keep track of our outstanding read to |decoder_|.
+  bool pending_read_;
+
   // Keeps track of whether we received and rendered the end of stream buffer.
   bool recieved_end_of_stream_;
   bool rendered_end_of_stream_;
 
-  // Keeps track of our pending reads.  We *must* have no pending reads before
-  // executing the pause callback, otherwise we breach the contract that all
-  // filters are idling.
-  //
-  // We use size_t since we compare against std::deque::size().
-  size_t pending_reads_;
-
   // Audio time at end of last call to FillBuffer().
   // TODO(ralphl): Update this value after seeking.
   base::TimeDelta last_fill_buffer_time_;
 
   // Filter callbacks.
   base::Closure pause_callback_;
   FilterStatusCB seek_cb_;
 
   base::Closure underflow_callback_;
 
   base::TimeDelta seek_timestamp_;
 
+  AudioDecoder::ReadCB read_cb_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioRendererBase);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_AUDIO_RENDERER_BASE_H_