Make it possible to set the display mode from the WebView API

Source/core/css/DisplayModeProperties.h

Index: Source/core/css/DisplayModeProperties.h
diff --git a/Source/core/css/DisplayModeProperties.h b/Source/core/css/DisplayModeProperties.h
deleted file mode 100644
index 17ac305e37163796063c0112fd61fdbb3747bd66..0000000000000000000000000000000000000000
--- a/Source/core/css/DisplayModeProperties.h
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright 2015 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 DisplayModeProperties_h
-#define DisplayModeProperties_h
-
-namespace blink {
-
-enum DisplayMode {
-    DisplayModeUndefined, // User for override setting (ie. not set).
-    DisplayModeBrowser,
-    DisplayModeMinimalUi,
-    DisplayModeStandalone,
-    DisplayModeFullscreen
-};
-
-}
-
-#endif