Remove calls to deprecated MessageLoop methods in chrome.

chrome/browser/media/router/mojo/media_router_mojo_impl_unittest.cc

 // 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.
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 #include <utility>
@@ skipping 1299 matching lines @@
                                      *extension_);
   }
 
   void RegisterMediaRouteProvider() {
     media_router_proxy_->RegisterMediaRouteProvider(
         std::move(media_route_provider_proxy_),
         base::Bind(&RegisterMediaRouteProviderHandler::Invoke,
                    base::Unretained(&provide_handler_)));
   }
 
-  void ProcessEventLoop() { message_loop_.RunUntilIdle(); }
+  void ProcessEventLoop() { base::RunLoop().RunUntilIdle(); }
 
   void ExpectWakeReasonBucketCount(MediaRouteProviderWakeReason reason,
                                    int expected_count) {
     histogram_tester_.ExpectBucketCount("MediaRouter.Provider.WakeReason",
                                         static_cast<int>(reason),
                                         expected_count);
   }
 
   void ExpectVersionBucketCount(MediaRouteProviderVersion version,
                                 int expected_count) {
@@ skipping 301 matching lines @@
   EXPECT_CALL(mock_media_route_provider_,
               UpdateMediaSinks(mojo::String(MediaSourceForDesktop().id())))
       .WillOnce(InvokeWithoutArgs([&run_loop2]() {
         run_loop2.Quit();
       }));
 
   run_loop2.Run();
 }
 
 }  // namespace media_router