Re-land:

views/window/native_window_delegate.h

 // Copyright (c) 2011 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 VIEWS_WIDGET_NATIVE_WINDOW_DELEGATE_H_
 #define VIEWS_WIDGET_NATIVE_WINDOW_DELEGATE_H_
 #pragma once
 
+namespace ui {
+class ThemeProvider;
+}
+
 namespace views {
 namespace internal {
 
 ////////////////////////////////////////////////////////////////////////////////
 // NativeWindowDelegate interface
 //
 //  An interface implemented by an object that receives notifications from a
 //  NativeWindow implementation.
 //
 class NativeWindowDelegate {
@@ skipping 38 matching lines @@
 
   // Called just before the native window is destroyed. This is the delegate's
   // last chance to do anything with the native window handle.
   virtual void OnNativeWindowDestroying() = 0;
 
   // Called just after the native window is destroyed.
   virtual void OnNativeWindowDestroyed() = 0;
 
   // Called when the native window's position or size has changed.
   virtual void OnNativeWindowBoundsChanged() = 0;
+
+  //
+  virtual Window* AsWindow() = 0;
+
+  //
+  virtual NativeWidgetDelegate* AsNativeWidgetDelegate() = 0;
 };
 
 }  // namespace internal
 }  // namespace views
 
 #endif  // VIEWS_WIDGET_NATIVE_WINDOW_DELEGATE_H_