Add audio_device_id in mojo media ServiceFactory CreateRenderer api.

media/mojo/interfaces/service_factory.mojom

 // Copyright 2015 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.
 
 module media.mojom;
 
 import "media/mojo/interfaces/audio_decoder.mojom";
 import "media/mojo/interfaces/content_decryption_module.mojom";
 import "media/mojo/interfaces/renderer.mojom";
 import "media/mojo/interfaces/video_decoder.mojom";
 
 // A factory interface to create media services. Renderers can only access
 // ContentDecryptionModules created in the same factory.
 interface ServiceFactory {
   // Creates an AudioDecoder service.
   CreateAudioDecoder(AudioDecoder& audio_decoder);
 
   // Creates a VideoDecoder service.
   CreateVideoDecoder(VideoDecoder& video_decoder);
 
   // Creates a Renderer service.
-  CreateRenderer(Renderer& renderer);
+  // Audio stream will be played on device_id, which is defined in
+  // media/audio/audio_device_description.h. If audio_device_id
+  // is null, kDefaultDeviceId will be used. 
+  CreateRenderer(Renderer& renderer,
+                 string? audio_device_id);

[alokp, 2016/06/01 00:06:14]

Since kDefaultDeviceId is already defined, may be it is better to make the
device-id as required parameter?

[tianyuwang1, 2016/06/02 03:32:32]

xhwang@ suggested that we should make this audio_device_id optional instead of
required.  so that when it's not set we can use the default device.  This is
what other places that use device_id is doing too.  If device_id is empty then
use default device.

 
   // Creates a ContentDecryptionModule service.
   CreateCdm(ContentDecryptionModule& cdm);
 };