Fix start/stop of html5 audio stream and race condition when pausing.

content/renderer/media/audio_renderer_impl.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.
 //
 // Audio rendering unit utilizing AudioDevice.
 //
 // This class lives inside three threads during it's lifetime, namely:
 // 1. Render thread.
 //    This object is created on the render thread.
 // 2. Pipeline thread
@@ skipping 57 matching lines @@
   // Convert number of bytes to duration of time using information about the
   // number of channels, sample rate and sample bits.
   base::TimeDelta ConvertToDuration(int bytes);
 
   // Methods called on pipeline thread ----------------------------------------
   void DoPlay();
   void DoPause();
   void DoSeek();
 
   // AudioDevice::RenderCallback implementation.
-  virtual void Render(const std::vector<float*>& audio_data,
-                      size_t number_of_frames,
-                      size_t audio_delay_milliseconds) OVERRIDE;
+  virtual size_t Render(const std::vector<float*>& audio_data,
+                        size_t number_of_frames,
+                        size_t audio_delay_milliseconds) OVERRIDE;
 
   // Accessors used by tests.
   base::Time earliest_end_time() const {
     return earliest_end_time_;
   }
 
   void set_earliest_end_time(const base::Time& earliest_end_time) {
     earliest_end_time_ = earliest_end_time;
   }
 
   uint32 bytes_per_second() const {
     return bytes_per_second_;
   }
 
   // Estimate earliest time when current buffer can stop playing.
   void UpdateEarliestEndTime(int bytes_filled,
                              base::TimeDelta request_delay,
                              base::Time time_now);
 
   // Used to calculate audio delay given bytes.
   uint32 bytes_per_second_;
 
   // A flag that indicates this filter is called to stop.
   bool stopped_;
 
+  // A flag that indicates that pre-populating call done.
+  bool prepopulated_;
+
   // audio_device_ is the sink (destination) for rendered audio.
   scoped_refptr<AudioDevice> audio_device_;
 
   // We're supposed to know amount of audio data OS or hardware buffered, but
   // that is not always so -- on my Linux box
   // AudioBuffersState::hardware_delay_bytes never reaches 0.
   //
   // As a result we cannot use it to find when stream ends. If we just ignore
   // buffered data we will notify host that stream ended before it is actually
   // did so, I've seen it done ~140ms too early when playing ~150ms file.
   //
   // Instead of trying to invent OS-specific solution for each and every OS we
   // are supporting, use simple workaround: every time we fill the buffer we
   // remember when it should stop playing, and do not assume that buffer is
   // empty till that time. Workaround is not bulletproof, as we don't exactly
   // know when that particular data would start playing, but it is much better
   // than nothing.
   base::Time earliest_end_time_;
 
   AudioParameters audio_parameters_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_