Deprecate HTMLVideoElement-specific prefixed fullscreen API

Source/core/frame/UseCounter.cpp

Index: Source/core/frame/UseCounter.cpp
diff --git a/Source/core/frame/UseCounter.cpp b/Source/core/frame/UseCounter.cpp
index 07b07f83c8eb293555ecefe6e48b9d55a4fc1a30..c9e955daf50f05bf8cf9b2e67cd65d0f7553c344 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -691,6 +691,24 @@ String UseCounter::deprecationMessage(Feature feature)
     case TextTrackCueConstructor:
         return "The 'TextTrackCue' constructor is deprecated. Please use 'VTTCue' instead.";
 
+    case PrefixedVideoSupportsFullscreen:
+        return "'HTMLVideoElement.webkitSupportsFullscreen' is deprecated. Its value is true if the video is loaded.";
+
+    case PrefixedVideoDisplayingFullscreen:
+        return "'HTMLVideoElement.webkitDisplayingFullscreen' is deprecated. Please use the 'fullscreenchange' and 'webkitfullscreenchange' events instead.";
+
+    case PrefixedVideoEnterFullscreen:
+        return "'HTMLVideoElement.webkitEnterFullscreen()' is deprecated. Please use 'Element.requestFullscreen()' and 'Element.webkitRequestFullscreen()' instead.";
+
+    case PrefixedVideoExitFullscreen:
+        return "'HTMLVideoElement.webkitExitFullscreen()' is deprecated. Please use 'Document.exitFullscreen()' and 'Document.webkitExitFullscreen()' instead.";
+
+    case PrefixedVideoEnterFullScreen:
+        return "'HTMLVideoElement.webkitEnterFullScreen()' is deprecated. Please use 'Element.requestFullscreen()' and 'Element.webkitRequestFullscreen()' instead.";
+
+    case PrefixedVideoExitFullScreen:
+        return "'HTMLVideoElement.webkitExitFullScreen()' is deprecated. Please use 'Document.exitFullscreen()' and 'Document.webkitExitFullscreen()' instead.";
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();