Use ScopedTaskEnvironment instead of MessageLoop in media unit tests.

media/gpu/ipc/service/gpu_jpeg_decode_accelerator_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 "media/gpu/ipc/service/gpu_jpeg_decode_accelerator.h"
 #include "base/bind.h"
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/threading/thread.h"
 #include "gpu/ipc/service/gpu_channel.h"
 #include "media/gpu/ipc/common/media_messages.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using testing::_;
 using testing::SaveArg;
 using testing::InvokeWithoutArgs;
 using testing::Return;
@@ skipping 55 matching lines @@
 
  protected:
   base::Thread io_thread_;
   MockFilteredSender gpu_channel_;
   std::unique_ptr<GpuJpegDecodeAccelerator> system_under_test_;
   base::SharedMemory output_frame_memory_;
 
  private:
   // This is required to allow base::ThreadTaskRunnerHandle::Get() from the
   // test execution thread.
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
 };
 
 // Tests that the communication for decoding a frame between the caller of
 // IPC:MessageFilter and the media::JpegDecodeAccelerator works as expected.
 TEST_F(GpuJpegDecodeAcceleratorTest, DecodeFrameCallArrivesAtDecoder) {
   static const int32_t kArbitraryRouteId = 123;
   auto io_task_runner = io_thread_.task_runner();
   auto main_task_runner = base::ThreadTaskRunnerHandle::Get();
   auto decoder = base::MakeUnique<MockJpegDecodeAccelerator>();
   auto* decoder_ptr = decoder.get();
@@ skipping 27 matching lines @@
   EXPECT_CALL(*decoder_ptr, Decode(_, _));
   io_task_runner->PostTaskAndReply(
       FROM_HERE,
       base::Bind(&GpuJpegDecodeAcceleratorTest::SendStubFrame,
                  base::Unretained(this), message_filter, kArbitraryRouteId),
       run_loop2.QuitClosure());
   run_loop2.Run();
 }
 
 }  // namespace media