aura: Destroy the compositor before destroying the backing window.

ui/gfx/win/window_impl.cc

Index: ui/gfx/win/window_impl.cc
diff --git a/ui/gfx/win/window_impl.cc b/ui/gfx/win/window_impl.cc
index 3ca3f900102feb7beb0788c1a5e0d4fbb65b1ee1..ff9fe57cf9dd8e5a2e21a6ea270c8c995e276084 100644
--- a/ui/gfx/win/window_impl.cc
+++ b/ui/gfx/win/window_impl.cc
@@ -226,10 +226,14 @@ HICON WindowImpl::GetDefaultWindowIcon() const {
 LRESULT WindowImpl::OnWndProc(UINT message, WPARAM w_param, LPARAM l_param) {
   LRESULT result = 0;
 
+  HWND hwnd = hwnd_;
+  if (message == WM_NCDESTROY)
+    hwnd_ = NULL;
+
   // Handle the message if it's in our message map; otherwise, let the system
   // handle it.
-  if (!ProcessWindowMessage(hwnd_, message, w_param, l_param, result))
-    result = DefWindowProc(hwnd_, message, w_param, l_param);
+  if (!ProcessWindowMessage(hwnd, message, w_param, l_param, result))
+    result = DefWindowProc(hwnd, message, w_param, l_param);
 
   return result;
 }