[Media Router] Custom Controls 1 - Add MediaStatus, MediaRouteController, and mojo interfaces

chrome/browser/media/router/mojo/media_status.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_router.mojom;
+
+import "mojo/common/time.mojom";
+
+// Represents the current state of a media content. This struct should be kept
+// free of details specific to Media Router, so that it can be moved to the
+// media namespace and be reused for other features in the future.
+struct MediaStatus {
+  // The main title of the media. For example, in a MediaStatus representing
+  // a YouTube Cast session, this could be the title of the video.
+  string title;
+
+  // Text describing the status of the media, or a secondary title. For example,
+  // in a MediaStatus representing a YouTube Cast session, this could be
+  // "YouTube".
+  string status;
+
+  // If this is true, the media can be played and paused through its
+  // MediaController.
+  bool can_play_pause;
+
+  // If this is true, the media can be muted and unmuted through its
+  // MediaController.
+  bool can_mute;
+
+  // If this is true, the media's volume can be changed through its
+  // MediaController.
+  bool can_set_volume;
+
+  // If this is true, the media's current playback position can be changed
+  // through its MediaController.
+  bool can_seek;
+
+  bool is_paused;
+
+  bool is_muted;
+
+  // Current volume of the media, with 1 being the highest and 0 being the
+  // lowest/no sound. When |is_muted| is true, there should be no sound
+  // regardless of |volume|.
+  float volume;
+
+  // The length of the media in milliseconds. A value of 0 indicates that this
+  // is a media with no set duration (e.g. a live stream).
+  mojo.common.mojom.TimeDelta duration;
+
+  // Current playback position in milliseconds. Must be less than or equal to
+  // |duration|.
+  mojo.common.mojom.TimeDelta current_time;

[dcheng, 2017/03/22 01:17:10]

FWIW, I'm uncertain of the granularity of these updates, but for things like
|current_time|, it seems like they might change pretty frequently. Perhaps it's
worth having a separate observer method for it rather than bundling it in the
MediaStatus struct.

(this is just a thought; I'm not asking for any concrete changes in this CL)

[takumif, 2017/03/22 21:54:30]

The updates will be once per second, so for now I'm thinking that it'd be okay
to be bundled.

+};
+
+// Interface for being notified whenever the MediaStatus of a media changes.
+// This interface should be kept free of details specific to Media Router, so
+// that it can be moved to the media namespace and be reused for other features
+// in the future.
+interface MediaStatusObserver {
+  OnMediaStatusUpdated(MediaStatus status);
+};