Media Remoting: Add mojo interfaces between browser and extension.

chrome/common/media_router/mojo/media_router.mojom

Index: chrome/common/media_router/mojo/media_router.mojom
diff --git a/chrome/common/media_router/mojo/media_router.mojom b/chrome/common/media_router/mojo/media_router.mojom
index ce99ec3e984a61335313a04af0c8b5c00a1563de..5f53bc1e50757b17af020ec37c9f8ba7be9282cc 100644
--- a/chrome/common/media_router/mojo/media_router.mojom
+++ b/chrome/common/media_router/mojo/media_router.mojom
@@ -6,6 +6,7 @@ module media_router.mojom;
 
 import "chrome/common/media_router/mojo/media_controller.mojom";
 import "chrome/common/media_router/mojo/media_status.mojom";
+import "media/mojo/interfaces/mirror_service_remoting.mojom";
 import "mojo/common/time.mojom";
 import "net/interfaces/ip_address.mojom";
 import "url/mojo/origin.mojom";
@@ -474,4 +475,11 @@ interface MediaRouter {
   // |messages|: A non-empty list of messages received.
   OnRouteMessagesReceived(string route_id,
                           array<RouteMessage> messages);
+
+  // Called when a MediaRemoter for a tab with |tab_id| is started. |remoter|
+  // can be used to access the MediaRemoter to control a media remoting session
+  // and send RPC messages to the remote device. |remoting_source| is bound to
+  // receive the updates/messages from MediaRemoter.
+  OnMediaRemoterCreated(int32 tab_id, media.mojom.MirrorServiceRemoter remoter,
+      media.mojom.MirrorServiceRemotingSource& remoting_source);
 };