[Media Router] Add Media Router Mojo impl code.

chrome/browser/media/router/presentation_media_sinks_observer_unittest.cc

Index: chrome/browser/media/router/presentation_media_sinks_observer_unittest.cc
diff --git a/chrome/browser/media/router/presentation_media_sinks_observer_unittest.cc b/chrome/browser/media/router/presentation_media_sinks_observer_unittest.cc
index 4a4639d3370ad72dc715a25ad90e72f259c6db93..45120e680ad39ca795f88378573069f6ac8e8a02 100644
--- a/chrome/browser/media/router/presentation_media_sinks_observer_unittest.cc
+++ b/chrome/browser/media/router/presentation_media_sinks_observer_unittest.cc
@@ -25,7 +25,7 @@ class PresentationMediaSinksObserverTest : public ::testing::Test {
   ~PresentationMediaSinksObserverTest() override {}
 
   void SetUp() override {
-    EXPECT_CALL(router_, RegisterMediaSinksObserver(_)).WillOnce(Return(true));
+    EXPECT_CALL(router_, RegisterMediaSinksObserver(_)).Times(1);
     observer_.reset(new PresentationMediaSinksObserver(
         &router_, &listener_,
         ForPresentationUrl("http://example.com/presentation.html")));