Media Remoting: Add RemotingController.

media/base/media_observer.h

Index: media/base/media_observer.h
diff --git a/media/base/media_observer.h b/media/base/media_observer.h
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+// 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 MEDIA_BASE_MEDIA_OBSERVER_H_
+#define MEDIA_BASE_MEDIA_OBSERVER_H_
+
+#include "media/base/cdm_context.h"
+#include "media/base/pipeline_metadata.h"
+
+namespace media {
+
+// This class is an observer of media player events.
+class MEDIA_EXPORT MediaObserver {
+ public:
+  MediaObserver();
+  virtual ~MediaObserver();
+
+  // Called when the media element entered/exited fullscreen.
+  virtual void OnEnteredFullscreen() = 0;
+  virtual void OnExitedFullscreen() = 0;
+
+  // Called when CDM is attached to the media element. The |cdm_context| is
+  // only guaranteed to be valid in this call.
+  virtual void OnSetCdm(CdmContext* cdm_context) = 0;
+
+  // Called after demuxer is initialized.
+  virtual void OnMetadataChanged(const PipelineMetadata& metadata) = 0;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_MEDIA_OBSERVER_H_