AudioRendererImpl: Don't advance time when rendering stops.

media/renderers/audio_renderer_impl.cc

Index: media/renderers/audio_renderer_impl.cc
diff --git a/media/renderers/audio_renderer_impl.cc b/media/renderers/audio_renderer_impl.cc
index c653bfccbdcbe95ac2c3ba0a522a46b9ec607e66..66fe2b79609856ac85bd7896754f36f3920aa48c 100644
--- a/media/renderers/audio_renderer_impl.cc
+++ b/media/renderers/audio_renderer_impl.cc
@@ -57,6 +57,7 @@ AudioRendererImpl::AudioRendererImpl(
       received_end_of_stream_(false),
       rendered_end_of_stream_(false),
       is_suspending_(false),
+      last_reported_media_time_(kNoTimestamp),
       weak_factory_(this) {
   audio_buffer_stream_->set_splice_observer(base::Bind(
       &AudioRendererImpl::OnNewSpliceBuffer, weak_factory_.GetWeakPtr()));
@@ -171,11 +172,27 @@ void AudioRendererImpl::SetMediaTime(base::TimeDelta time) {
   last_render_time_ = stop_rendering_time_ = base::TimeTicks();
   first_packet_timestamp_ = kNoTimestamp;
   audio_clock_.reset(new AudioClock(time, audio_parameters_.sample_rate()));
+  last_reported_media_time_ = kNoTimestamp;
 }
 
 base::TimeDelta AudioRendererImpl::CurrentMediaTime() {
   base::AutoLock auto_lock(lock_);
 
+  // Re-use last reported time if rendering has stopped to avoid confusing blink
+  // layer (avoid currentTime advancing after signaling buffer underflow).
+  // TODO(chcunningham): Do this in blink instead. Patching it here for now
+  // because HTMLMediaElement's currentTime is a mess.
+  if (!rendering_ && last_reported_media_time_ != kNoTimestamp) {
+    // If rendering stops, be sure to at least report the front time of the most
+    // recently rendered audio buffer.
+    if (last_reported_media_time_ < audio_clock_->front_timestamp())
+      last_reported_media_time_ = audio_clock_->front_timestamp();
+
+    DVLOG(3) << __func__ << " Returning cached time while rendering stopped:"
+             << last_reported_media_time_.InMicroseconds();
+    return last_reported_media_time_;
+  }
+
   // Return the current time based on the known extents of the rendered audio
   // data plus an estimate based on the last time those values were calculated.
   base::TimeDelta current_media_time = audio_clock_->front_timestamp();
@@ -186,6 +203,7 @@ base::TimeDelta AudioRendererImpl::CurrentMediaTime() {
       current_media_time = audio_clock_->back_timestamp();
   }
 
+  last_reported_media_time_ = current_media_time;
   return current_media_time;
 }
 
@@ -430,6 +448,7 @@ void AudioRendererImpl::Initialize(DemuxerStream* stream,
 
   audio_clock_.reset(
       new AudioClock(base::TimeDelta(), audio_parameters_.sample_rate()));
+  last_reported_media_time_ = kNoTimestamp;
 
   audio_buffer_stream_->Initialize(
       stream, base::Bind(&AudioRendererImpl::OnAudioBufferStreamInitialized,