aura: Destroy the compositor before destroying the backing window.

ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
index 71d690f918eccbe2b3b23f909b9f6516d8085537..3cba99c8c627348083ab1eaab1408721bcbe8f4f 100644
--- a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
@@ -142,7 +142,6 @@ DesktopWindowTreeHostX11::DesktopWindowTreeHostX11(
 }
 
 DesktopWindowTreeHostX11::~DesktopWindowTreeHostX11() {
-  DestroyCompositor();
   root_window_->window()->ClearProperty(kHostForRootWindow);
   aura::client::SetWindowMoveClient(root_window_->window(), NULL);
   desktop_native_widget_aura_->OnDesktopWindowTreeHostDestroyed(root_window_);
@@ -320,6 +319,9 @@ void DesktopWindowTreeHostX11::CloseNow() {
   desktop_native_widget_aura_->root_window_event_filter()->RemoveHandler(
       x11_window_event_filter_.get());
 
+  // Destroy the compositor before destroying the |xwindow_|.

[sky, 2014/01/13 23:51:29]

nit: documenting what the code does isn't helpful for future generations.
Instead document why the code is the way it is.

[danakj, 2014/01/13 23:54:39]

Good point, done.

+  DestroyCompositor();

[Ben Goodger (Google), 2014/01/13 23:11:47]

So, I wonder if we should do this on windows too. I find it confusing when one
platform has an ordering dependency/difference like this and another does not.

If so, the appropriate place to call this in DesktopRootWindowHostWin is in
DRWHW::HandleDestroying(). Then, WindowTreeHost::DestroyCompositor can DCHECK
that GetAcceleratedWidget() returns non-NULL (though I think we may also want to
NULL out hwnd_ in HandleDestroyed()).

[danakj, 2014/01/13 23:54:39]

It seems that when the compositor shuts down and tries to swap on windows, and
the window is gone, that it does not cause the test to crash.
It's not at all obvious to me how to go about destroying the hwnd (I don't see
any destruction of the hwnd_ in the window_impl.cc class?

+
   open_windows().remove(xwindow_);
   // Actually free our native resources.
   base::MessagePumpX11::Current()->RemoveDispatcherForWindow(xwindow_);