[chromecast] Moves CastAudioOutputStream::Backend to CMA thread.

chromecast/media/cma/test/mock_media_pipeline_backend_factory.h

+// Copyright 2016 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.
+
+#ifndef CHROMECAST_MEDIA_CMA_TEST_MOCK_MEDIA_PIPELINE_BACKEND_FACTORY_H_
+#define CHROMECAST_MEDIA_CMA_TEST_MOCK_MEDIA_PIPELINE_BACKEND_FACTORY_H_
+
+#include "chromecast/media/cma/backend/media_pipeline_backend_factory.h"
+#include "chromecast/public/media/media_pipeline_backend.h"
+#include "chromecast/public/media/media_pipeline_device_params.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace chromecast {
+namespace media {
+
+class MockMediaPipelineBackendFactory : public MediaPipelineBackendFactory {
+ public:
+  MockMediaPipelineBackendFactory();
+  ~MockMediaPipelineBackendFactory() override;
+
+  MOCK_METHOD1(
+      CreateBackend,
+      std::unique_ptr<MediaPipelineBackend>(const MediaPipelineDeviceParams&));
+};
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_MEDIA_CMA_TEST_MOCK_MEDIA_PIPELINE_BACKEND_FACTORY_H_