Implement disabling and enabling media tracks

media/renderers/audio_renderer_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/renderers/audio_renderer_impl.h"
 
 #include <math.h>
 #include <stddef.h>
 #include <algorithm>
 #include <utility>
@@ skipping 273 matching lines @@
   DoFlush_Locked();
 }
 
 void AudioRendererImpl::DoFlush_Locked() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   lock_.AssertAcquired();
 
   DCHECK(!pending_read_);
   DCHECK_EQ(state_, kFlushed);
 
+  ended_timestamp_ = kInfiniteDuration();

[chcunningham, 2016/06/24 23:32:55]

This seems like the right thing - just curious how you found this wasn't being
done?

[servolk, 2016/06/25 00:36:33]

I've been testing this CL manually, trying a bunch of different things
(enable/disable a/v streams, seek/pause/resume while one of the streams is
disabled, etc), and noticed that audio stream playback would sometimes stall
when re-enabling and audio stream after it's been disabled and a seek to a
different position has occured. I've debugged that stall and noticed that we
need to reset |ended_timestamp_| during the Flush even if that Flush is not
followed by SetMediaTime, since when we are restarting the audio stream, we do a
flush, but we don't do an explicit SetMediaTime.

   audio_buffer_stream_->Reset(base::Bind(&AudioRendererImpl::ResetDecoderDone,
                                          weak_factory_.GetWeakPtr()));
 }
 
 void AudioRendererImpl::ResetDecoderDone() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   {
     base::AutoLock auto_lock(lock_);
 
     DCHECK_EQ(state_, kFlushed);
@@ skipping 655 matching lines @@
   DCHECK_NE(buffering_state_, buffering_state);
   lock_.AssertAcquired();
   buffering_state_ = buffering_state;
 
   task_runner_->PostTask(
       FROM_HERE, base::Bind(&AudioRendererImpl::OnBufferingStateChange,
                             weak_factory_.GetWeakPtr(), buffering_state_));
 }
 
 }  // namespace media