Make win_aura work without ash.

ui/aura/root_window_host_win.h

Index: ui/aura/root_window_host_win.h
===================================================================
--- ui/aura/root_window_host_win.h	(revision 134107)
+++ ui/aura/root_window_host_win.h	(working copy)
@@ -10,6 +10,10 @@
 #include "ui/aura/root_window_host.h"
 #include "ui/base/win/window_impl.h"
 
+namespace ui {
+class ViewProp;
+}
+
 namespace aura {
 
 class RootWindowHostWin : public RootWindowHost, public ui::WindowImpl {
@@ -19,6 +23,7 @@
 
   // RootWindowHost:
   virtual void SetRootWindow(RootWindow* root_window) OVERRIDE;
+  virtual RootWindow* GetRootWindow() OVERRIDE;
   virtual gfx::AcceleratedWidget GetAcceleratedWidget() OVERRIDE;
   virtual void Show() OVERRIDE;
   virtual void ToggleFullScreen() OVERRIDE;
@@ -74,6 +79,8 @@
   DWORD saved_window_style_;
   DWORD saved_window_ex_style_;
 
+  scoped_ptr<ui::ViewProp> prop_;
+
   DISALLOW_COPY_AND_ASSIGN(RootWindowHostWin);
 };