Pass origin to StartObservingMediaSinks.

chrome/browser/media/router/media_router.mojom

Index: chrome/browser/media/router/media_router.mojom
diff --git a/chrome/browser/media/router/media_router.mojom b/chrome/browser/media/router/media_router.mojom
index 9a2f5e7e712f6fa1f0ef0764150f4f385d3a02b2..28a53bbfcf2870372c43765e0c7e86c4a939b4bb 100644
--- a/chrome/browser/media/router/media_router.mojom
+++ b/chrome/browser/media/router/media_router.mojom
@@ -215,10 +215,12 @@ interface MediaRouteProvider {
       => (bool sent);
 
   // Starts querying for sinks capable of displaying |media_source|.
-  StartObservingMediaSinks(string media_source);
+  // |origin| can be used to optionally verify that the origin is

[mark a. foltz, 2016/03/03 22:58:36]

I would say:
|origin| is the origin of the client that is requesting media sinks.
It may be used to verify that |origin| is authorized to receive sinks for
|media_source|.
 

[matt.boetger, 2016/03/04 00:22:10]

This is the second time you have suggested a change to this.  I will change it
this time, but any future change of your mind should require another CL to
prevent this from continuing ad nauseam.

+  // authorized to issue the query.
+  StartObservingMediaSinks(string media_source, string origin);
 
   // Stops querying sinks for |media_source|.

[mark a. foltz, 2016/03/03 22:58:36]

And:
|origin| is the origin of the client that started the query.

[matt.boetger, 2016/03/04 00:22:10]

Done.

-  StopObservingMediaSinks(string media_source);
+  StopObservingMediaSinks(string media_source, string origin);
 
   // Starts reporting the state of active media routes via
   // OnRoutesUpdated() in the context of the |media_source|.  The
@@ -302,7 +304,7 @@ interface MediaRouter {
       (string instance_id);
 
   // Called when the Media Route Manager receives a new list of sinks.
-  OnSinksReceived(string media_source, array<MediaSink> sinks);
+  OnSinksReceived(string media_source, string origin, array<MediaSink> sinks);
 
   // Called when issues are reported for media routes.
   OnIssue(Issue issue);