Use ScopedTaskEnvironment instead of MessageLoop in chrome unit tests.

chrome/browser/ui/desktop_ios_promotion/sms_service_unittest.cc

 // Copyright 2017 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 "chrome/browser/ui/desktop_ios_promotion/sms_service.h"
 
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "components/signin/core/browser/account_tracker_service.h"
 #include "components/signin/core/browser/fake_profile_oauth2_token_service.h"
 #include "components/signin/core/browser/fake_signin_manager.h"
 #include "components/signin/core/browser/test_signin_client.h"
 #include "net/http/http_status_code.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
@@ skipping 120 matching lines @@
   }
 
   TestingSMSService* sms_service() { return &sms_service_; }
 
   void SetNextRequestResponseData(int response_code,
                                   const std::string& response_body) {
     sms_service_.SetNextRequestResponseData(response_code, response_body);
   }
 
  private:
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   FakeProfileOAuth2TokenService token_service_;
   AccountTrackerService account_tracker_;
   TestSigninClient signin_client_;
   FakeSigninManagerBase signin_manager_;
   scoped_refptr<net::URLRequestContextGetter> url_request_context_;
   TestingSMSService sms_service_;
 
   DISALLOW_COPY_AND_ASSIGN(SMSServiceTest);
 };
 
@@ skipping 31 matching lines @@
       base::Bind(&TestingSMSService::QueryPhoneNumberCallbackFailed,
                  base::Unretained(sms_service())));
   base::RunLoop().RunUntilIdle();
   std::string send_sms_invalid = "{}";
   sms_service()->SetNextRequestResponseData(net::HTTP_OK, send_sms_invalid);
   sms_service()->SendSMS(
       promo_id, base::Bind(&TestingSMSService::QueryPhoneNumberCallbackFailed,
                            base::Unretained(sms_service())));
   base::RunLoop().RunUntilIdle();
 }