media: Support creation and SetCdm() for mojo based CDM.

media/mojo/interfaces/media_renderer.mojom

 // 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.
 
 module mojo;
 
 import "media/mojo/interfaces/demuxer_stream.mojom";
 import "media/mojo/interfaces/media_types.mojom";
 
 [Client=MediaRendererClient]
@@ skipping 10 matching lines @@
   Flush() => ();
 
   // Starts rendering from |time_usec|.
   StartPlayingFrom(int64 time_usec);
 
   // Updates the current playback rate. The default playback rate should be 1.
   SetPlaybackRate(float playback_rate);
 
   // Sets the output volume. The default volume should be 1.
   SetVolume(float volume);
+
+  // Sets the CDM to be used by the renderer. Returns whether the CDM is
+  // successfully attached.

[ddorwin, 2015/01/06 00:57:28]

It returns the result of something that is not mentioned in the main
documentation (first sentence) for the method. I think we decided to keep the
name, but we should at least include "attach" in the main description.

[xhwang, 2015/01/06 19:54:54]

Done.

+  SetCdm(int32 cdm_id) => (bool success);
 };
 
 interface MediaRendererClient {
   // Called to report media time advancement by |time_usec|.
   // |time_usec| and |max_time_usec| can be used to interpolate time between
   // calls to OnTimeUpdate().
   // |max_time_usec| is typically the media timestamp of the last audio frame
   //     buffered by the audio hardware.
   // |max_time_usec| must be greater or equal to |time_usec|.
   OnTimeUpdate(int64 time_usec, int64 max_time_usec);
 
   // Called to report buffering state changes, see media_types.mojom.
   OnBufferingStateChange(BufferingState state);
 
   // Executed when rendering has reached the end of stream.
   OnEnded();
 
   // Executed if any error was encountered during decode or rendering. If
   // this error happens during an operation that has a completion callback,
   // OnError() will be called before firing the completion callback.
   OnError();
 };