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

content/browser/web_contents/web_contents_impl.cc

 // 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.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <utility>
@@ skipping 4204 matching lines @@
 }
 
 bool WebContentsImpl::HideDownloadUI() const {
   return is_overlay_content_;
 }
 
 bool WebContentsImpl::HasPersistentVideo() const {
   return has_persistent_video_;
 }
 
+bool WebContentsImpl::HasActiveFullscreenDominantVideo() const {
+  return media_web_contents_observer_->HasActiveFullscreenDominantVideo();
+}
+
 bool WebContentsImpl::IsFocusedElementEditable() {
   RenderFrameHostImpl* frame = GetFocusedFrame();
   return frame && frame->has_focused_editable_element();
 }
 
 void WebContentsImpl::ClearFocusedElement() {
   if (auto* frame = GetFocusedFrame())
     frame->ClearFocusedElement();
 }
 
@@ skipping 1156 matching lines @@
     RenderViewHost* render_view_host = RenderViewHost::From(render_widget_host);
     if (!render_view_host)
       continue;
     render_view_host_set.insert(render_view_host);
   }
   for (RenderViewHost* render_view_host : render_view_host_set)
     render_view_host->OnWebkitPreferencesChanged();
 }
 
 }  // namespace content