[chromecast] Bind and run mojo media services on cma thread.

media/mojo/services/mojo_media_client.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_media_client.h"
 
 namespace media {
 
-MojoMediaClient::MojoMediaClient() {}
+MojoMediaClient::MojoMediaClient(
+    scoped_refptr<base::SingleThreadTaskRunner> media_task_runner)
+    : media_task_runner_(std::move(media_task_runner)) {}
 
 MojoMediaClient::~MojoMediaClient() {}
 
 void MojoMediaClient::Initialize() {}
 
 scoped_ptr<AudioDecoder> MojoMediaClient::CreateAudioDecoder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
   return nullptr;
 }
 
@@ skipping 10 matching lines @@
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner) {
   return nullptr;
 }
 
 scoped_ptr<CdmFactory> MojoMediaClient::CreateCdmFactory(
     mojo::shell::mojom::InterfaceProvider* interface_provider) {
   return nullptr;
 }
 
 }  // namespace media