Use ScopedTaskEnvironment instead of MessageLoop in components unit tests.

components/sync/js/sync_js_controller_unittest.cc

 // 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.
 
 #include "components/sync/js/sync_js_controller.h"
 
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/values.h"
 #include "components/sync/js/js_event_details.h"
 #include "components/sync/js/js_test_util.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace syncer {
 namespace {
 
 using ::testing::_;
 using ::testing::InSequence;
 using ::testing::Mock;
 using ::testing::StrictMock;
 
 class SyncJsControllerTest : public testing::Test {
  protected:
   void PumpLoop() { base::RunLoop().RunUntilIdle(); }
 
  private:
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 };
 
 TEST_F(SyncJsControllerTest, Events) {
   InSequence dummy;
   SyncJsController sync_js_controller;
 
   base::DictionaryValue details_dict1, details_dict2;
   details_dict1.SetString("foo", "bar");
   details_dict2.SetInteger("baz", 5);
   JsEventDetails details1(&details_dict1), details2(&details_dict2);
@@ skipping 12 matching lines @@
   sync_js_controller.HandleJsEvent("anotherevent", details2);
   sync_js_controller.RemoveJsEventHandler(&event_handler1);
   sync_js_controller.RemoveJsEventHandler(&event_handler2);
   sync_js_controller.HandleJsEvent("droppedevent", details2);
 
   PumpLoop();
 }
 
 }  // namespace
 }  // namespace syncer