aura: Destroy the compositor before destroying the backing window.

ui/gfx/win/window_impl.cc

 // 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.
 
 #include "ui/gfx/win/window_impl.h"
 
 #include <list>
 
 #include "base/debug/alias.h"
 #include "base/memory/singleton.h"
@@ skipping 201 matching lines @@
   }
   if (!destroyed)
     destroyed_ = NULL;
 
   CheckWindowCreated(hwnd_);
 
   // The window procedure should have set the data for us.
   CHECK_EQ(this, GetWindowUserData(hwnd));
 }
 
+void WindowImpl::SetDestroyed() { hwnd_ = NULL; }

[Ben Goodger (Google), 2014/01/15 19:16:20]

sorry to continue to nitpick this, but could you do this by handling
WM_NCDESTROY at the end of WndProc() below (after it calls OnWndProc)... this
makes sure that hwnd_ is reset properly for all users of this class, rather than
just those that call SetDestroyed().

BTW I made one assertion that was incorrect which I will correct now for the
record: When WM_NCDESTROY is sent your hwnd_ is not invalid, but it probably is
shortly after you return. MSDN defines WM_DESTROY as "before child windows are
destroyed" and WM_NCDESTROY as "after child windows are destroyed."

[danakj, 2014/01/15 19:23:52]

I see, OK done. I set hwnd_ to NULL after calling window->OnWndProc, since the
OnWndProc uses the hwnd_. This means I can't DCHECK in
DesktopWindowTreeHostWin::HandleDestroyed anymore, so I've removed that.

+
 HICON WindowImpl::GetDefaultWindowIcon() const {
   return NULL;
 }
 
 LRESULT WindowImpl::OnWndProc(UINT message, WPARAM w_param, LPARAM l_param) {
   LRESULT result = 0;
 
   // 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))
@@ skipping 31 matching lines @@
   return window->OnWndProc(message, w_param, l_param);
 }
 
 ATOM WindowImpl::GetWindowClassAtom() {
   HICON icon = GetDefaultWindowIcon();
   ClassInfo class_info(initial_class_style(), icon);
   return ClassRegistrar::GetInstance()->RetrieveClassAtom(class_info);
 }
 
 }  // namespace gfx