Use ScopedTaskEnvironment instead of MessageLoop in components unit tests.

components/invalidation/impl/gcm_network_channel_unittest.cc

 // Copyright 2014 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/invalidation/impl/gcm_network_channel.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/base64url.h"
 #include "base/run_loop.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "google_apis/gaia/google_service_auth_error.h"
 #include "net/url_request/test_url_fetcher_factory.h"
 #include "net/url_request/url_request_test_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace syncer {
 
 class TestGCMNetworkChannelDelegate : public GCMNetworkChannelDelegate {
@@ skipping 182 matching lines @@
   InvalidatorState get_last_invalidator_state() {
     return last_invalidator_state_;
   }
 
   void RunLoopUntilIdle() {
     base::RunLoop run_loop;
     run_loop.RunUntilIdle();
   }
 
  private:
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   TestGCMNetworkChannelDelegate* delegate_;
   std::unique_ptr<GCMNetworkChannel> gcm_network_channel_;
   scoped_refptr<net::TestURLRequestContextGetter> request_context_getter_;
   std::unique_ptr<net::FakeURLFetcherFactory> url_fetcher_factory_;
   int url_fetchers_created_count_;
   std::string last_echo_token_;
   InvalidatorState last_invalidator_state_;
 };
 
 void TestNetworkChannelURLFetcher::AddExtraRequestHeader(
@@ skipping 248 matching lines @@
   delegate()->request_token_callback.Run(
       GoogleServiceAuthError::AuthErrorNone(), "access.token");
   RunLoopUntilIdle();
   EXPECT_EQ(url_fetchers_created_count(), 3);
   // Echo_token should be from second message.
   EXPECT_EQ("echo.token", get_last_echo_token());
 }
 #endif
 
 }  // namespace syncer