Implement disabling and enabling media tracks

media/filters/ffmpeg_demuxer.cc

Index: media/filters/ffmpeg_demuxer.cc
diff --git a/media/filters/ffmpeg_demuxer.cc b/media/filters/ffmpeg_demuxer.cc
index 0a4dad5c54666414aeb0227aec7e57c5206f9fd5..b088c57ce3922e80d4d573b3adc4d7a487954cdd 100644
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -267,6 +267,7 @@ FFmpegDemuxerStream::FFmpegDemuxerStream(
       last_packet_timestamp_(kNoTimestamp()),
       last_packet_duration_(kNoTimestamp()),
       video_rotation_(VIDEO_ROTATION_0),
+      is_enabled_(true),
       fixup_negative_timestamps_(false) {
   DCHECK(demuxer_);
 
@@ -613,6 +614,12 @@ void FFmpegDemuxerStream::Read(const ReadCB& read_cb) {
     return;
   }
 
+  if (!is_enabled_) {
+    DVLOG(1) << "Read from disabled stream, returning EOS";
+    base::ResetAndReturn(&read_cb_).Run(kOk, DecoderBuffer::CreateEOSBuffer());
+    return;
+  }
+
   SatisfyPendingRead();
 }
 
@@ -676,6 +683,24 @@ VideoRotation FFmpegDemuxerStream::video_rotation() {
   return video_rotation_;
 }
 
+bool FFmpegDemuxerStream::enabled() const {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  return is_enabled_;
+}
+
+void FFmpegDemuxerStream::set_enabled(bool enabled, base::TimeDelta timestamp) {

[chcunningham, 2016/06/02 23:49:43]

I feel like we need some logic here to drop frames after we enable until we
observe the first key frame. I get that we have one file position, so we cant
seek like we did in chunk demuxer.

+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (enabled == is_enabled_)
+    return;
+
+  is_enabled_ = enabled;
+  if (!is_enabled_ && !read_cb_.is_null()) {
+    DVLOG(1) << "Read from disabled stream, returning EOS";
+    base::ResetAndReturn(&read_cb_).Run(kOk, DecoderBuffer::CreateEOSBuffer());
+    return;
+  }
+}
+
 void FFmpegDemuxerStream::SetLiveness(Liveness liveness) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK_EQ(liveness_, LIVENESS_UNKNOWN);
@@ -1538,7 +1563,8 @@ void FFmpegDemuxer::OnReadFrameDone(ScopedAVPacket packet, int result) {
     }
 
     FFmpegDemuxerStream* demuxer_stream = streams_[packet->stream_index];
-    demuxer_stream->EnqueuePacket(std::move(packet));
+    if (demuxer_stream->enabled())
+      demuxer_stream->EnqueuePacket(std::move(packet));
   }
 
   // Keep reading until we've reached capacity.