[Chromecast] Fix media session blocking tests.

content/public/test/mock_media_session.h

+// Copyright (c) 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.
+
+#ifndef CONTENT_PUBLIC_TEST_MOCK_MEDIA_SESSION_H_
+#define CONTENT_PUBLIC_TEST_MOCK_MEDIA_SESSION_H_
+
+#include "content/public/browser/media_session.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace content {
+
+class MockMediaSession : public MediaSession {

[Zhiqiang Zhang (Slow), 2017/01/20 16:27:56]

I think the major change is to make content::MediaSession mockable. As it is
done now, maybe there's no need to put MockMediaSession in content/public/test
anymore? As it's only mocked from chromecast/, you can put it in an anonymous
namespace in the test file.

[derekjchow1, 2017/01/23 21:04:32]

SGTM. Done.

+ public:
+  MockMediaSession();
+  ~MockMediaSession() override;
+
+  MOCK_METHOD1(Resume, void(content::MediaSession::SuspendType));
+  MOCK_METHOD1(Suspend, void(content::MediaSession::SuspendType));
+  MOCK_METHOD1(Stop, void(content::MediaSession::SuspendType));
+  MOCK_METHOD0(StartDucking, void());
+  MOCK_METHOD0(StopDucking, void());
+  MOCK_METHOD1(DidReceiveAction, void(blink::mojom::MediaSessionAction));
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MockMediaSession);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_TEST_MOCK_MEDIA_SESSION_H_