Implement FullScreen using top layer.

Source/web/tests/WebFrameTest.cpp

Index: Source/web/tests/WebFrameTest.cpp
diff --git a/Source/web/tests/WebFrameTest.cpp b/Source/web/tests/WebFrameTest.cpp
index 2ea914dcf633bdbefd3dd7fec1a736ce30f1fb0a..57588bd6afd2fa8575c43c3e9f3b2661769edd25 100644
--- a/Source/web/tests/WebFrameTest.cpp
+++ b/Source/web/tests/WebFrameTest.cpp
@@ -63,7 +63,6 @@
 #include "core/html/HTMLMediaElement.h"
 #include "core/input/EventHandler.h"
 #include "core/layout/HitTestResult.h"
-#include "core/layout/LayoutFullScreen.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/DeprecatedPaintLayerCompositor.h"
 #include "core/loader/DocumentLoader.h"
@@ -6484,7 +6483,8 @@ TEST_P(ParameterizedWebFrameTest, FullscreenLayerSize)
     ASSERT_TRUE(Fullscreen::isFullScreen(*document));
 
     // Verify that the element is sized to the viewport.
-    LayoutFullScreen* fullscreenLayoutObject = Fullscreen::from(*document).fullScreenLayoutObject();
+    Element* fullscreenElement = Fullscreen::currentFullScreenElementFrom(*document);
+    LayoutBox* fullscreenLayoutObject = toLayoutBox(fullscreenElement->layoutObject());
     EXPECT_EQ(viewportWidth, fullscreenLayoutObject->logicalWidth().toInt());
     EXPECT_EQ(viewportHeight, fullscreenLayoutObject->logicalHeight().toInt());
 
@@ -6588,7 +6588,8 @@ TEST_P(ParameterizedWebFrameTest, FullscreenSubframe)
     webViewImpl->layout();
 
     // Verify that the element is sized to the viewport.
-    LayoutFullScreen* fullscreenLayoutObject = Fullscreen::from(*document).fullScreenLayoutObject();
+    Element* fullscreenElement = Fullscreen::currentFullScreenElementFrom(*document);
+    LayoutBox* fullscreenLayoutObject = toLayoutBox(fullscreenElement->layoutObject());
     EXPECT_EQ(viewportWidth, fullscreenLayoutObject->logicalWidth().toInt());
     EXPECT_EQ(viewportHeight, fullscreenLayoutObject->logicalHeight().toInt());