[Media Router] Add ProvideSinks() Mojo API

chrome/browser/media/router/mojo/media_router.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_router.mojom;
 
 import "mojo/common/time.mojom";
 import "url/mojo/url.mojom";
 
 // Represents an output sink to which media can be routed.
@@ skipping 333 matching lines @@
   // Indicates that the Media Router is interested in finding a sink that
   // matches |search_criteria| and is compatible with the source urn
   // |media_source|. |search_criteria| should contain an exact copy of the user
   // input. The user's current domain is also used to search.  The domain is the
   // hosted domain of the user's signed-in identity, or empty if the user has no
   // domain or is not signed in.
   SearchSinks(string sink_id,
               string media_source,
               SinkSearchCriteria search_criteria) =>
                   (string sink_id);
+
+  // Called when Media Router finishes sink discovery.
+  // |sinks| represents a list of sinks discovered by Media Router.
+  OnSinksDiscovered(array<MediaSink> sinks);

[mark a. foltz, 2017/02/10 01:23:55]

It's a little tricky to distinguish this from OnSinksReceived below.

Maybe name this ProvideSinks() to make it clear this are sinks discovered by the
MR and passed to the MRP?  Derek, do you have any ideas?

Do you need to handle the origin and media_source data passed with
OnSinksReceived?   Maybe we should prioritize simplifying the API to eliminate
those.

[imcheng, 2017/02/10 22:45:18]

ProvideSinks sounds good. This method does not need |origin| or |media_source|
as it is not a response to a sink query. 

Also the comment could be something like:

Called when the list of MediaSinks discovered by Media Router has been updated.
The sinks are supplied to the MediaRouteProvider so that they can be used for
other operations, such as route creation.

[zhaobin, 2017/02/16 22:56:35]

Done.

 };
 
 // Interface for a service which observes state changes across media
 // sources, sinks, and issues.
 interface MediaRouter {
 
   // Represents overall media sink availability states.
   // UNAVAILABLE - No sinks are available.
   // PER_SOURCE - Sinks are available, but are only compatible with specific
   //              media sources.
@@ skipping 55 matching lines @@
 
   // Called when the a batch of messages arrives from the media sink for the
   // route given by |route_id|.
   // |StartListeningForRouteMessages| must be called first in order to receive
   // messages.
   // |route_id|: ID of route of the messages.
   // |messages|: A non-empty list of messages received.
   OnRouteMessagesReceived(string route_id,
                           array<RouteMessage> messages);
 };