Use HTMLMediaElement's helpers for the video fullscreen button

Source/core/html/shadow/MediaControlElements.cpp

Index: Source/core/html/shadow/MediaControlElements.cpp
diff --git a/Source/core/html/shadow/MediaControlElements.cpp b/Source/core/html/shadow/MediaControlElements.cpp
index c5455e7c3d2dbedbe003bcd67d0cc97e03436059..3bec1c9f638747f1230b65f128a49036c57b2fb3 100644
--- a/Source/core/html/shadow/MediaControlElements.cpp
+++ b/Source/core/html/shadow/MediaControlElements.cpp
@@ -32,7 +32,6 @@
 
 #include "bindings/v8/ExceptionStatePlaceholder.h"
 #include "core/dom/DOMTokenList.h"
-#include "core/dom/FullscreenElementStack.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/events/MouseEvent.h"
 #include "core/frame/LocalFrame.h"
@@ -492,10 +491,10 @@ PassRefPtrWillBeRawPtr<MediaControlFullscreenButtonElement> MediaControlFullscre
 void MediaControlFullscreenButtonElement::defaultEventHandler(Event* event)
 {
     if (event->type() == EventTypeNames::click) {
-        if (FullscreenElementStack::isActiveFullScreenElement(mediaElement()))
-            FullscreenElementStack::from(document()).webkitCancelFullScreen();
+        if (mediaElement().isFullscreen())
+            mediaElement().exitFullscreen();
         else
-            FullscreenElementStack::from(document()).requestFullScreenForElement(mediaElement(), 0, FullscreenElementStack::ExemptIFrameAllowFullScreenRequirement);
+            mediaElement().enterFullscreen();
         event->setDefaultHandled();
     }
     HTMLInputElement::defaultEventHandler(event);