Avoid double task trampoline for Pipeline state transitions.

media/mojo/services/mojo_renderer_impl.cc

 // Copyright 2014 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/mojo/services/mojo_renderer_impl.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 37 matching lines @@
   // Bind the mojo InterfacePtr to the message pipe on the
   // current thread so we can use it. The MojoRendererImpl object
   // is constructed on another thread so we can't do it in the
   // constructor and must pass a message pipe around since
   // InterfacePtr's are tied to the message loop they were created on.
   remote_media_renderer_.Bind(remote_media_renderer_pipe_.Pass());
   DCHECK(remote_media_renderer_);
   remote_media_renderer_.set_client(this);
 
   demuxer_stream_provider_ = demuxer_stream_provider;
-  // |init_cb| can be called on other thread.
   init_cb_ = init_cb;
   ended_cb_ = ended_cb;
   error_cb_ = error_cb;
   buffering_state_cb_ = buffering_state_cb;
 
   // Create audio and video mojo::DemuxerStream and bind its lifetime to the
   // pipe.
   DemuxerStream* const audio =
       demuxer_stream_provider_->GetStream(DemuxerStream::AUDIO);
   DemuxerStream* const video =
@@ skipping 139 matching lines @@
 
 void MojoRendererImpl::OnInitialized() {
   DVLOG(1) << __FUNCTION__;
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(!init_cb_.is_null());
 
   base::ResetAndReturn(&init_cb_).Run();
 }
 
 }  // namespace media