Implement pepper flash fullscreen on Mac

ui/base/cocoa/underlay_opengl_hosting_window.h

Index: ui/base/cocoa/underlay_opengl_hosting_window.h
===================================================================
--- ui/base/cocoa/underlay_opengl_hosting_window.h	(revision 0)
+++ ui/base/cocoa/underlay_opengl_hosting_window.h	(revision 0)
@@ -0,0 +1,33 @@
+// 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.
+
+#ifndef UI_BASE_COCOA_UNDERLAY_OPENGL_HOSTING_WINDOW_H_
+#define UI_BASE_COCOA_UNDERLAY_OPENGL_HOSTING_WINDOW_H_
+#pragma once
+
+#import <Cocoa/Cocoa.h>
+
+// Protocol implemented by windows that need to be informed explicitly about
+// underlay surfaces.
+@protocol UnderlayableSurface
+- (void)underlaySurfaceAdded;
+- (void)underlaySurfaceRemoved;
+@end
+
+// Common base class for windows that host a OpenGL surface that renders under
+// the window. Contains methods relating to hole punching so that the OpenGL
+// surface is visible through the window.
+@interface UnderlayOpenGLHostingWindow : NSWindow<UnderlayableSurface> {
+ @private
+  int underlaySurfaceCount_;
+}
+
+// Informs the window that an underlay surface has been added/removed. The
+// window is non-opaque while underlay surfaces are present.
+- (void)underlaySurfaceAdded;
+- (void)underlaySurfaceRemoved;
+
+@end
+
+#endif  // UI_BASE_COCOA_UNDERLAY_OPENGL_HOSTING_WINDOW_H_