Media Remoting: Add mojo interfaces between browser and extension.

media/mojo/interfaces/mirror_service_remoting.mojom

+// Copyright 2017 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/remoting_common.mojom";
+
+// Interface used by the source to start/stop remoting and send data to the
+// sink.
+interface MirrorServiceRemoter {
+  // Start a remoting session. Either MirrorServiceRemotingSource.OnStarted() or

[imcheng, 2017/06/22 01:13:27]

Please use third person verbs when describing the method, i.e. Starts / Stops /
Sends etc.

similarly for below and remoting_common.mojom

[xjz, 2017/06/23 19:02:42]

Done.

+  // OnStartFailed() will be called to indicate success or failure. Once
+  // OnStarted() has been invoked, the source may then make calls to
+  // SendMessageToSink() and expect messages from the remote via
+  // MirrorServiceRemotingSource.OnMessageFromSink().
+  Start();
+
+  // Start remoting the media data streams. This is called after Start() to
+  // indicate audio/video bitstream data is ready to be consumed.
+  StartDataStreams(bool has_audio, bool has_video);
+
+  // Stop remoting media. Messages in both directions will be dropped after this
+  // point as well as any pending or in-transit media bitstream data.
+  Stop(media.mojom.RemotingStopReason reason);
+
+  // Send |message| to the sink. |message| is a serialized protobuf from
+  // src/media/remoting/proto.
+  SendMessageToSink(array<uint8> message);
+};
+
+// Interface used for sending notifications back to the source's control logic,
+// and to pass messages from the sink back to the source.
+interface MirrorServiceRemotingSource {
+  // Notify the source that the sink is now available to start remoting. It is
+  // up to the source's control logic to decide whether/when to start remoting.
+  OnSinkAvailable(media.mojom.RemotingSinkCapabilities capabilities);
+
+  // One of these is called after the source attempts to start remoting. If
+  // OnStarted() is called, messages may begin flowing; and this will continue
+  // until OnStopped() is called. On the other hand, if OnStartFailed() is
+  // called, then no messages are being passed between source and sink and
+  // remoting is not taking place.
+  OnStarted();
+  OnStartFailed(media.mojom.RemotingStartFailReason reason);
+
+  // Called after the remoting data streams are created. Setting the
+  // |audio/video_stream_id| to -1 indicates there is no audio/video stream.
+  OnDataStreamsStarted(int32 audio_stream_id, int32 video_stream_id);
+
+  // Pass a |message| from the sink back to the source. The |message| consists
+  // of a serialized protobuf from src/media/remoting/proto. This will only be
+  // called after OnStarted() and before OnStopped().
+  OnMessageFromSink(array<uint8> message);
+
+  // Notify the source that remoting has terminated. This may or may not be in
+  // response to a Remoter.Stop() call, as other events (possibly external) may
+  // have caused remoting to end.
+  OnStopped(media.mojom.RemotingStopReason reason);
+
+  // Notify the source that error occurs while streaming.
+  OnError();
+};