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

content/renderer/media/audio_renderer_impl.cc

Index: content/renderer/media/audio_renderer_impl.cc
===================================================================
--- content/renderer/media/audio_renderer_impl.cc	(revision 113847)
+++ content/renderer/media/audio_renderer_impl.cc	(working copy)
@@ -38,7 +38,8 @@
 AudioRendererImpl::AudioRendererImpl()
     : AudioRendererBase(),
       bytes_per_second_(0),
-      stopped_(false) {
+      stopped_(false),
+      prepopulated_(false) {
   // We create the AudioDevice here because it must be created in the
   // main thread.  But we don't yet know the audio format (sample-rate, etc.)
   // at this point.  Later, when OnInitialize() is called, we have
@@ -192,14 +193,22 @@
   audio_device_->Pause(true);
 }
 
-void AudioRendererImpl::Render(const std::vector<float*>& audio_data,
-                               size_t number_of_frames,
-                               size_t audio_delay_milliseconds) {
+size_t AudioRendererImpl::Render(const std::vector<float*>& audio_data,
+                                 size_t number_of_frames,
+                                 size_t audio_delay_milliseconds) {
+  // Ignore first pre-populating call.
+  // It is issued when creating the stream, and there was no request for data
+  // from AudioSyncReader. We will get that first request when player issue
+  // "play" command.
+  if (!prepopulated_) {
+    prepopulated_ = true;
+    return 0;
+  }
   if (stopped_ || GetPlaybackRate() == 0.0f) {
     // Output silence if stopped.
     for (size_t i = 0; i < audio_data.size(); ++i)
       memset(audio_data[i], 0, sizeof(float) * number_of_frames);
-    return;
+    return 0;
   }
 
   // Adjust the playback delay.
@@ -227,6 +236,7 @@
                              request_delay,
                              time_now >= earliest_end_time_);
   DCHECK_LE(filled, buf_size);
+  UpdateEarliestEndTime(filled, request_delay, time_now);
 
   uint32 filled_frames = filled / bytes_per_frame;
 
@@ -246,4 +256,5 @@
       memset(audio_data[channel_index], 0, sizeof(float) * frames_to_zero);
     }
   }
+  return filled_frames;
 }