[Chromecast] Fix media session blocking tests.

content/public/browser/media_session.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 CONTENT_PUBLIC_BROWSER_MEDIA_SESSION_H_
 #define CONTENT_PUBLIC_BROWSER_MEDIA_SESSION_H_
 
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "content/common/content_export.h"
 
 namespace blink {
 namespace mojom {
 enum class MediaSessionAction;
 }  // namespace mojom
 }  // namespace blink
 
 namespace content {
 
+class MediaSessionObserver;
 class WebContents;
 
 // MediaSession manages the media session and audio focus for a given
 // WebContents. There is only one MediaSession per WebContents.
 //
 // MediaSession allows clients to observe its changes via MediaSessionObserver,
 // and allows clients to resume/suspend/stop the managed players.
-class MediaSession {
+class CONTENT_EXPORT MediaSession {

[Zhiqiang Zhang (Slow), 2017/01/30 12:09:11]

Revert this change as MediaSession is back to a pure interface.

[derekjchow1, 2017/02/01 01:22:19]

Done.

  public:
   enum class SuspendType {
     // Suspended by the system because a transient sound needs to be played.
     SYSTEM,
     // Suspended by the UI.
     UI,
     // Suspended by the page via script or user interaction.
     CONTENT,
   };
 
   // Returns the MediaSession associated to this WebContents. Creates one if
   // none is currently available.
   CONTENT_EXPORT static MediaSession* Get(WebContents* contents);
 
-  virtual ~MediaSession() = default;
+  virtual ~MediaSession();

[Zhiqiang Zhang (Slow), 2017/01/30 12:09:10]

Revert this change as MediaSession is back to a pure interface.

[derekjchow1, 2017/02/01 01:22:18]

Done.

 
   // Resume the media session.
   // |type| represents the origin of the request.
   virtual void Resume(SuspendType suspend_type) = 0;
 
   // Resume the media session.
   // |type| represents the origin of the request.
   virtual void Suspend(SuspendType suspend_type) = 0;
 
   // Resume the media session.
   // |type| represents the origin of the request.
   virtual void Stop(SuspendType suspend_type) = 0;
 
   // Tell the media session a user action has performed.
   virtual void DidReceiveAction(blink::mojom::MediaSessionAction action) = 0;
 
   // Let the media session start ducking such that the volume multiplier is
   // reduced.
   virtual void StartDucking() = 0;
 
   // Let the media session stop ducking such that the volume multiplier is
   // recovered.
   virtual void StopDucking() = 0;
 
  protected:
-  MediaSession() = default;
+  MediaSession();

[Zhiqiang Zhang (Slow), 2017/01/30 12:09:11]

Revert this change as MediaSession is back to a pure interface.

[derekjchow1, 2017/02/01 01:22:18]

Done.

+
+  base::ObserverList<MediaSessionObserver>& observers() { return observers_; }

[mlamouri (slow - plz ping), 2017/01/28 02:01:40]

Can you move the implementation to the .cc file?

[Zhiqiang Zhang (Slow), 2017/01/30 12:09:10]

I think you don't need this any more. Revert this change and keep it in
media_session_impl.cc

[derekjchow1, 2017/02/01 01:22:18]

Removed (only in MediaSessionImpl now).

[derekjchow1, 2017/02/01 01:22:19]

Done.

+
+ private:
+  friend class MediaSessionObserver;
+
+  void AddObserver(MediaSessionObserver* observer);

[Zhiqiang Zhang (Slow), 2017/01/30 12:09:10]

Make it pure-virtual. Keep it as private should be OK.

[derekjchow1, 2017/02/01 01:22:19]

Done.

+  void RemoveObserver(MediaSessionObserver* observer);

[Zhiqiang Zhang (Slow), 2017/01/30 12:09:10]

ditto

[derekjchow1, 2017/02/01 01:22:18]

Done.

+
+  base::ObserverList<MediaSessionObserver> observers_;

[Zhiqiang Zhang (Slow), 2017/01/30 12:09:10]

ditto (same reason as `observers()`)

[derekjchow1, 2017/02/01 01:22:18]

Done.

 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_MEDIA_SESSION_H_