Provide a WebContents API to discover the playback of a fullscreen video.

content/browser/media/media_web_contents_observer.h

 // Copyright 2014 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_BROWSER_MEDIA_MEDIA_WEB_CONTENTS_OBSERVER_H_
 #define CONTENT_BROWSER_MEDIA_MEDIA_WEB_CONTENTS_OBSERVER_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 24 matching lines @@
 // forwards them to the corresponding managers. The managers are responsible
 // for sending IPCs back to the RenderFrameObservers at the render side.
 class CONTENT_EXPORT MediaWebContentsObserver : public WebContentsObserver {
  public:
   explicit MediaWebContentsObserver(WebContents* web_contents);
   ~MediaWebContentsObserver() override;
 
   // Called by WebContentsImpl when the audible state may have changed.
   void MaybeUpdateAudibleState();
 
+  // Called by WebContentsImpl to know if an active player is effectively
+  // fullscreen. That means that the video is either fullscreen or it is the
+  // content of a fullscreen page (in other words, a fullscreen video with
+  // custom controls).
+  // It should only be called while the WebContents is fullscreen.
+  bool HasActiveEffectivelyFullscreenVideo() const;
+
   // WebContentsObserver implementation.
   void WebContentsDestroyed() override;
   void RenderFrameDeleted(RenderFrameHost* render_frame_host) override;
   bool OnMessageReceived(const IPC::Message& message,
                          RenderFrameHost* render_frame_host) override;
   void WasShown() override;
   void WasHidden() override;
 
   bool has_audio_power_save_blocker_for_testing() const {
     return !!audio_power_save_blocker_;
@@ skipping 12 matching lines @@
   void OnMediaDestroyed(RenderFrameHost* render_frame_host, int delegate_id);
   void OnMediaPaused(RenderFrameHost* render_frame_host,
                      int delegate_id,
                      bool reached_end_of_stream);
   void OnMediaPlaying(RenderFrameHost* render_frame_host,
                       int delegate_id,
                       bool has_video,
                       bool has_audio,
                       bool is_remote,
                       media::MediaContentType media_content_type);
+  void OnMediaEffectivelyFullscreenChange(RenderFrameHost* render_frame_host,
+                                          int delegate_id,
+                                          bool is_fullscreen);
 
   // Clear |render_frame_host|'s tracking entry for its power save blockers.
   void ClearPowerSaveBlockers(RenderFrameHost* render_frame_host);
 
   // Creates an audio or video power save blocker respectively.
   void CreateAudioPowerSaveBlocker();
   void CreateVideoPowerSaveBlocker();
 
   // Releases the audio power save blockers if |active_audio_players_| is empty.
   // Likewise, releases the video power save blockers if |active_video_players_|
@@ skipping 12 matching lines @@
   // entries are added to |removed_players|.
   void RemoveAllMediaPlayerEntries(RenderFrameHost* render_frame_host,
                                    ActiveMediaPlayerMap* player_map,
                                    std::set<MediaPlayerId>* removed_players);
 
   // Tracking variables and associated power save blockers for media playback.
   ActiveMediaPlayerMap active_audio_players_;
   ActiveMediaPlayerMap active_video_players_;
   std::unique_ptr<device::PowerSaveBlocker> audio_power_save_blocker_;
   std::unique_ptr<device::PowerSaveBlocker> video_power_save_blocker_;
+  base::Optional<MediaPlayerId> fullscreen_player_;
 
   MediaSessionControllersManager session_controllers_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaWebContentsObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_MEDIA_WEB_CONTENTS_OBSERVER_H_