[Media Router] Add ProvideSinks() Mojo API

chrome/browser/media/router/mojo/media_router.mojom

Index: chrome/browser/media/router/mojo/media_router.mojom
diff --git a/chrome/browser/media/router/mojo/media_router.mojom b/chrome/browser/media/router/mojo/media_router.mojom
index f9072db62cdbc65b1512e91dbf3e3649d0c7084a..4cb81b7ab88808ae31e25bda2836411297e6efd9 100644
--- a/chrome/browser/media/router/mojo/media_router.mojom
+++ b/chrome/browser/media/router/mojo/media_router.mojom
@@ -351,6 +351,10 @@ interface MediaRouteProvider {
               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