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

content/browser/web_contents/web_contents_impl.h

 // Copyright (c) 2012 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_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <stdint.h>
 
 #include <functional>
@@ skipping 768 matching lines @@
                        int active_match_ordinal,
                        bool final_update);
 
   // Modify the counter of connected devices for this WebContents.
   void IncrementBluetoothConnectedDeviceCount();
   void DecrementBluetoothConnectedDeviceCount();
 
   // Called when the WebContents gains or loses a persistent video.
   void SetHasPersistentVideo(bool value);
 
+  // Whether the WebContents has an active fullscreen video or a dominant video
+  // while the WebContents is fullscreen.
+  // |IsFullscreen| must return |true| when this method is called.

[liberato (no reviews please), 2017/02/14 23:00:01]

why?

[mlamouri (slow - plz ping), 2017/02/17 16:36:24]

The DCHECK() is just because it would basically mean checking the things
multiple time. Instead of having the callers make the call and the method check
too, better to have a "contract" which requires that callers know what they are
doing. The current expectations is that this would only be called while
fullscreen. It could change though.

+  virtual bool HasActiveFullscreenDominantVideo() const;
+
 #if defined(OS_ANDROID)
   // Called by FindRequestManager when all of the find match rects are in.
   void NotifyFindMatchRectsReply(int version,
                                  const std::vector<gfx::RectF>& rects,
                                  const gfx::RectF& active_rect);
 #endif
 
  private:
   friend class WebContentsObserver;
   friend class WebContents;  // To implement factory methods.
@@ skipping 719 matching lines @@
   // Adds/removes a callback called on creation of each new WebContents.
   static void AddCreatedCallbackForTesting(const CreatedCallback& callback);
   static void RemoveCreatedCallbackForTesting(const CreatedCallback& callback);
 
   DISALLOW_COPY_AND_ASSIGN(FriendZone);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_