media: add basic MediaRenderer mojom and TypeConverters

mojo/services/public/interfaces/media/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.
+
+import "mojo/services/public/interfaces/media/media_types.mojom"
+
+module mojo {
+
+[Client=MediaRendererClient]
+interface MediaRenderer {
+  // Initializes the Renderer, calling back with status upon completion.
+  Initialize(handle<data_pipe_consumer> demuxer_stream) =>
+      (PipelineStatus pipeline_status);
+
+  // Discards any buffered data, executing callback when completed.
+  Flush() => ();
+
+  // Starts rendering from |time|.
+  StartPlayingFrom(int64 time_delta_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);
+
+  /* TODO(tim): Figure out these
+  GetMediaTime() => (int64 time_delta_usec);

[xhwang, 2014/08/22 23:30:02]

Since we have OnTimeAdvanced, we probably don't need this at all. The
media::MojoRendererImpl can implement this based on the time updates.

+  HasAudio()
+  HasVideo()
+  */
+};
+
+interface MediaRendererClient {
+  OnNewStatistics(PipelineStatistics statistics);

[xhwang, 2014/08/22 23:30:02]

nit: OnStatistics

+  OnTimeAdvanced(int64 time_delta_usec);

[xhwang, 2014/08/22 23:30:02]

OnTimeUpdate() would be a more media-ish term :)

+  OnBufferingStateChange(BufferingState state);
+  OnEndOfStream();

[xhwang, 2014/08/22 23:30:02]

OnEnded() to be more consistent with media Pipeline terms.

+  OnPipelineError(PipelineStatus error);

[xhwang, 2014/08/22 23:30:02]

Renderer knows nothing about Pipeline. So just OnError()?

+};
+
+}
+
+/* REMOVE THIS
+
+e.g
+
+class MojoRendererImpl : public media::Renderer,
+                         mojo::MediaRendererClient {
+
+  ...
+  mojo::MediaRendererPtr renderer;
+  <magic_thing>->ConnectToService("lib with InterfaceImpl<MediaRenderer>", &renderer);
+
+
+};
+*/