MediaRouterAction: Only observe Media Routes when there is a local route.

chrome/browser/media/router/local_media_routes_observer.h

Index: chrome/browser/media/router/local_media_routes_observer.h
diff --git a/chrome/browser/media/router/local_media_routes_observer.h b/chrome/browser/media/router/local_media_routes_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..3598ae66b7f812b0c715ea072d473ee52e0d366a
--- /dev/null
+++ b/chrome/browser/media/router/local_media_routes_observer.h
@@ -0,0 +1,32 @@
+// 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.
+
+#ifndef CHROME_BROWSER_MEDIA_ROUTER_LOCAL_MEDIA_ROUTES_OBSERVER_H_
+#define CHROME_BROWSER_MEDIA_ROUTER_LOCAL_MEDIA_ROUTES_OBSERVER_H_
+
+#include "base/macros.h"
+
+namespace media_router {
+
+class MediaRouter;
+
+// Base class for observing whether local routes exist in the Media Router.
+class LocalMediaRoutesObserver {
+ public:
+  explicit LocalMediaRoutesObserver(MediaRouter* router);
+  virtual ~LocalMediaRoutesObserver();
+
+  // Called when a local route has been successfully created or if there has
+  // been an update to the list of routes.
+  virtual void OnHasLocalRouteUpdated(bool has_local_route) {}
+
+ private:
+  MediaRouter* const router_;
+
+  DISALLOW_COPY_AND_ASSIGN(LocalMediaRoutesObserver);
+};
+
+}  // namespace media_router
+
+#endif  // CHROME_BROWSER_MEDIA_ROUTER_LOCAL_MEDIA_ROUTES_OBSERVER_H_