Add GetCurrentRoutes() to MediaRouter API, ensure dialog has routes at init

chrome/browser/media/router/media_router_base.h

 // 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_MEDIA_ROUTER_BASE_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_BASE_H_
 
 #include <set>
 #include <vector>
 
@@ skipping 14 matching lines @@
   std::unique_ptr<PresentationConnectionStateSubscription>
   AddPresentationConnectionStateChangedCallback(
       const MediaRoute::Id& route_id,
       const content::PresentationConnectionStateChangedCallback& callback)
       override;
 
   // Called when the incognito profile for this instance is being shut down.
   // This will terminate all incognito media routes.
   void OnIncognitoProfileShutdown() override;
 
+  std::vector<MediaRoute> GetCurrentRoutes() const override;
+
  protected:
   FRIEND_TEST_ALL_PREFIXES(MediaRouterMojoImplTest,
                            PresentationConnectionStateChangedCallback);
   FRIEND_TEST_ALL_PREFIXES(MediaRouterMojoImplTest,
                            PresentationConnectionStateChangedCallbackRemoved);
   FRIEND_TEST_ALL_PREFIXES(MediaRouterBaseTest, CreatePresentationIds);
   FRIEND_TEST_ALL_PREFIXES(MediaRouterBaseTest, NotifyCallbacks);
 
   MediaRouterBase();
 
@@ skipping 39 matching lines @@
 
   std::unique_ptr<InternalMediaRoutesObserver> internal_routes_observer_;
   bool initialized_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterBase);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_BASE_H_