[Media Router] Remove the extension ID getter from MRMojoImpl

chrome/browser/ui/webui/media_router/media_router_ui.h

Index: chrome/browser/ui/webui/media_router/media_router_ui.h
diff --git a/chrome/browser/ui/webui/media_router/media_router_ui.h b/chrome/browser/ui/webui/media_router/media_router_ui.h
index bc58d4d4c185c6a39e4d31f55c3d697ab47faa21..bb70fa414823fefabace724e42eed3732afb340f 100644
--- a/chrome/browser/ui/webui/media_router/media_router_ui.h
+++ b/chrome/browser/ui/webui/media_router/media_router_ui.h
@@ -44,6 +44,7 @@ class Browser;
 namespace media_router {
 
 class CreatePresentationConnectionRequest;
+class EventPageRequestManager;
 class IssuesObserver;
 class MediaRoute;
 class MediaRouter;
@@ -414,6 +415,9 @@ class MediaRouterUI
   // Pointer to the MediaRouter for this instance's BrowserContext.
   MediaRouter* router_;
 
+  // Request manager for the Media Router component extension.
+  const EventPageRequestManager* event_page_request_manager_;
+
   // The start time for UI initialization metrics timer. When a dialog has been
   // been painted and initialized with initial data, this should be cleared.
   base::Time start_time_;