MSE: Fix logic bugs with high precision duration

media/blink/webmediaplayer_impl.cc

Index: media/blink/webmediaplayer_impl.cc
diff --git a/media/blink/webmediaplayer_impl.cc b/media/blink/webmediaplayer_impl.cc
index 03b11fb029fee3a10beeb932a0c0a33fb3d41955..023cb9904d4cf73494a0dd05dc8ef85000c2b4b1 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -696,7 +696,19 @@ double WebMediaPlayerImpl::duration() const {
   if (ready_state_ == WebMediaPlayer::ReadyStateHaveNothing)
     return std::numeric_limits<double>::quiet_NaN();
 
-  return GetPipelineDuration();
+  // Use duration from ChunkDemuxer when present. MSE allows users to specify
+  // duration as a double. This propagates to the rest of the pipeline as a
+  // TimeDelta with potentially reduced precision (limited to Microseconds).
+  // ChunkDemuxer returns the full-precision user-specified double. This ensures
+  // users can "get" the exact duration they "set".
+  if (chunk_demuxer_) {
+    return chunk_demuxer_->GetDuration();

[wolenetz, 2016/12/16 00:56:51]

Is WMPI::duration() ever queried in a code path where earlier in the stack the
ChunkDemuxer lock is still acquired? I seem to recall an ancient double-lock
potential around this.

[chcunningham, 2017/01/03 17:48:05]

Not that I'm aware of. I did some searching and couldn't find anything. This
would have to be something like an event bubbled up from ChunkDemuxer. The main
avenue for that is the demuxer "client", which is Pipeline::RenderWrapper, which
does a good job of consistently posting things to the main thread for them to
bubble up to WMPI.

+  }

[mlamouri (slow - plz ping), 2016/12/15 10:20:51]

style: no { }

[chcunningham, 2017/01/03 17:48:05]

Done.

+
+  base::TimeDelta pipeline_duration = pipeline_.GetMediaDuration();
+  return (pipeline_duration == kInfiniteDuration)

[mlamouri (slow - plz ping), 2016/12/15 10:20:51]

nit: () are not needed

[chcunningham, 2017/01/03 17:48:05]

Done.

+             ? std::numeric_limits<double>::infinity()
+             : pipeline_duration.InSecondsF();
 }
 
 double WebMediaPlayerImpl::timelineOffset() const {
@@ -1659,17 +1671,6 @@ blink::WebAudioSourceProvider* WebMediaPlayerImpl::getAudioSourceProvider() {
   return audio_source_provider_.get();
 }
 
-double WebMediaPlayerImpl::GetPipelineDuration() const {
-  base::TimeDelta duration = pipeline_.GetMediaDuration();
-
-  // Return positive infinity if the resource is unbounded.
-  // http://www.whatwg.org/specs/web-apps/current-work/multipage/video.html#dom-media-duration
-  if (duration == kInfiniteDuration)
-    return std::numeric_limits<double>::infinity();
-
-  return duration.InSecondsF();
-}
-
 static void GetCurrentFrameAndSignal(
     VideoFrameCompositor* compositor,
     scoped_refptr<VideoFrame>* video_frame_out,