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..b790e4cb7f94f6d440dd326bc8d5f70768a56e0a 100644
--- a/ui/gfx/win/window_impl.cc
+++ b/ui/gfx/win/window_impl.cc
@@ -219,6 +219,8 @@ void WindowImpl::Init(HWND parent, const Rect& bounds) {
   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;
 }