[Media Router] Add some SetForTest() functions to DialMediaSinkService and update unit tests

chrome/browser/media/router/discovery/dial/dial_registry.h

 // Copyright (c) 2012 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_DISCOVERY_DIAL_DIAL_REGISTRY_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_REGISTRY_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 44 matching lines @@
 
    protected:
     virtual ~Observer() {}
   };
 
   static DialRegistry* GetInstance();
 
   // Called by the DIAL API when event listeners are added or removed. The dial
   // service is started after the first listener is added and stopped after the
   // last listener is removed.
-  void OnListenerAdded();
-  void OnListenerRemoved();
+  virtual void OnListenerAdded();
+  virtual void OnListenerRemoved();
 
   // pass a reference of |observer| to allow it to notify on DIAL device events.
   // This class does not take ownership of observer.
   virtual void RegisterObserver(Observer* observer);
   virtual void UnregisterObserver(Observer* observer);
 
   // Called by the DIAL API to try to kickoff a discovery if there is not one
   // already active.
   bool DiscoverNow();
 
@@ skipping 129 matching lines @@
                            TestRemovingListenerDoesNotClearList);
   FRIEND_TEST_ALL_PREFIXES(DialRegistryTest, TestNetworkEventConnectionLost);
   FRIEND_TEST_ALL_PREFIXES(DialRegistryTest,
                            TestNetworkEventConnectionRestored);
   DISALLOW_COPY_AND_ASSIGN(DialRegistry);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_DISCOVERY_DIAL_DIAL_REGISTRY_H_