[TO 54] 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 ce94d751ce42fbe6eb1a3dcb845fe977734775f2..1349cb03b262f0ae931da431bf42d17053adf273 100644
--- a/media/renderers/audio_renderer_impl.cc
+++ b/media/renderers/audio_renderer_impl.cc
@@ -102,10 +102,12 @@ AudioRendererImpl::~AudioRendererImpl() {
 void AudioRendererImpl::StartTicking() {
   DVLOG(1) << __func__;
   DCHECK(task_runner_->BelongsToCurrentThread());
+
+  base::AutoLock auto_lock(lock_);
+
   DCHECK(!rendering_);
   rendering_ = true;
 
-  base::AutoLock auto_lock(lock_);
   // Wait for an eventual call to SetPlaybackRate() to start rendering.
   if (playback_rate_ == 0) {
     DCHECK(!sink_playing_);
@@ -132,10 +134,12 @@ void AudioRendererImpl::StartRendering_Locked() {
 void AudioRendererImpl::StopTicking() {
   DVLOG(1) << __func__;
   DCHECK(task_runner_->BelongsToCurrentThread());
+
+  base::AutoLock auto_lock(lock_);
+
   DCHECK(rendering_);
   rendering_ = false;
 
-  base::AutoLock auto_lock(lock_);
   // Rendering should have already been stopped with a zero playback rate.
   if (playback_rate_ == 0) {
     DCHECK(!sink_playing_);
@@ -172,11 +176,27 @@ void AudioRendererImpl::SetMediaTime(base::TimeDelta time) {
   first_packet_timestamp_ = kNoTimestamp;
   last_media_timestamp_ = base::TimeDelta();
   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();
@@ -201,6 +221,7 @@ base::TimeDelta AudioRendererImpl::CurrentMediaTime() {
 
   DVLOG(2) << __func__ << ": " << current_media_time;
   last_media_timestamp_ = current_media_time;
+  last_reported_media_time_ = current_media_time;
   return current_media_time;
 }
 
@@ -445,6 +466,7 @@ 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,