Use ScopedTaskEnvironment instead of MessageLoop in media unit tests.

media/cdm/cdm_adapter_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 "media/cdm/cdm_adapter.h"
 
 #include <stdint.h>
 #include <memory>
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "media/base/cdm_callback_promise.h"
 #include "media/base/cdm_key_information.h"
 #include "media/base/content_decryption_module.h"
 #include "media/base/mock_filters.h"
 #include "media/cdm/cdm_file_io.h"
 #include "media/cdm/external_clear_key_test_helper.h"
 #include "media/cdm/simple_cdm_allocator.h"
 #include "media/media_features.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 212 matching lines @@
 
   // Helper class to load/unload External Clear Key Library.
   ExternalClearKeyTestHelper helper_;
 
   // Keep track of the loaded CDM.
   scoped_refptr<ContentDecryptionModule> adapter_;
 
   // |session_id_| is the latest result of calling CreateSession().
   std::string session_id_;
 
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 
   DISALLOW_COPY_AND_ASSIGN(CdmAdapterTest);
 };
 
 TEST_F(CdmAdapterTest, Initialize) {
   InitializeAndExpect(ExternalClearKeyLibrary(), SUCCESS);
 }
 
 TEST_F(CdmAdapterTest, BadLibraryPath) {
   InitializeAndExpect(base::FilePath(FILE_PATH_LITERAL("no_library_here")),
@@ skipping 56 matching lines @@
 TEST_F(CdmAdapterTest, UpdateSessionWithBadData) {
   InitializeAndExpect(ExternalClearKeyLibrary(), SUCCESS);
 
   std::vector<uint8_t> key_id(kKeyId, kKeyId + arraysize(kKeyId));
   CreateSessionAndExpect(EmeInitDataType::WEBM, key_id, SUCCESS);
 
   UpdateSessionAndExpect(SessionId(), "random data", FAILURE, true);
 }
 
 }  // namespace media