Use ScopedTaskEnvironment instead of MessageLoop in components unit tests.

components/ntp_tiles/icon_cacher_impl_unittest.cc

 // Copyright 2016 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 "components/ntp_tiles/icon_cacher_impl.h"
 
 #include <set>
 #include <utility>
 
 #include "base/files/scoped_temp_dir.h"
 #include "base/memory/ptr_util.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
 #include "base/test/mock_callback.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/test/test_simple_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/favicon/core/favicon_client.h"
 #include "components/favicon/core/favicon_service_impl.h"
 #include "components/favicon/core/favicon_util.h"
 #include "components/history/core/browser/history_database_params.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/image_fetcher/core/image_decoder.h"
 #include "components/image_fetcher/core/image_fetcher.h"
 #include "components/image_fetcher/core/request_metadata.h"
@@ skipping 145 matching lines @@
               loop->Quit();
             },
             &image, &loop),
         &tracker);
     loop.Run();
     return image;
   }
 
   void WaitForTasksToFinish() { task_runner_->RunUntilIdle(); }
 
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   PopularSites::Site site_;
   std::unique_ptr<MockImageFetcher> image_fetcher_;
   std::unique_ptr<MockImageDecoder> image_decoder_;
   base::ScopedTempDir history_dir_;
   history::HistoryService history_service_;
   favicon::FaviconServiceImpl favicon_service_;
   scoped_refptr<base::TestSimpleTaskRunner> task_runner_;
   NiceMock<MockResourceDelegate> mock_resource_delegate_;
 };
 
@@ skipping 156 matching lines @@
               Eq(gfx::Size(64, 64)));  // Compares dimensions, not objects.
 
   // Let the fetcher continue and wait for the second call of the callback.
   fetch_loop.Run();  // Wait for the updated image.
   EXPECT_THAT(GetCachedIconFor(site_.url, favicon_base::TOUCH_ICON).Size(),
               Eq(gfx::Size(128, 128)));  // Compares dimensions, not objects.
 }
 
 }  // namespace
 }  // namespace ntp_tiles