aura: Destroy the compositor before destroying the backing window.

ui/views/widget/desktop_aura/desktop_root_window_host_x11.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/views/widget/desktop_aura/desktop_root_window_host_x11.h"
 
 #include <X11/extensions/shape.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xregion.h>
@@ skipping 124 matching lines @@
       drag_drop_client_(NULL),
       current_cursor_(ui::kCursorNull),
       native_widget_delegate_(native_widget_delegate),
       desktop_native_widget_aura_(desktop_native_widget_aura),
       content_window_(NULL),
       window_parent_(NULL),
       custom_window_shape_(NULL) {
 }
 
 DesktopWindowTreeHostX11::~DesktopWindowTreeHostX11() {
-  DestroyCompositor();
   root_window_->window()->ClearProperty(kHostForRootWindow);
   aura::client::SetWindowMoveClient(root_window_->window(), NULL);
   desktop_native_widget_aura_->OnDesktopWindowTreeHostDestroyed(root_window_);
   if (custom_window_shape_)
     XDestroyRegion(custom_window_shape_);
 }
 
 // static
 aura::Window* DesktopWindowTreeHostX11::GetContentWindowForXID(XID xid) {
   aura::RootWindow* root = aura::RootWindow::GetForAcceleratedWidget(xid);
@@ skipping 157 matching lines @@
   if (window_parent_) {
     window_parent_->window_children_.erase(this);
     window_parent_ = NULL;
   }
 
   // Remove the event listeners we've installed. We need to remove these
   // because otherwise we get assert during ~RootWindow().
   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_);
   XDestroyWindow(xdisplay_, xwindow_);
   xwindow_ = None;
 
   desktop_native_widget_aura_->OnHostClosed();
 }
 
 aura::WindowTreeHost* DesktopWindowTreeHostX11::AsWindowTreeHost() {
@@ skipping 1213 matching lines @@
   if (linux_ui) {
     ui::NativeTheme* native_theme = linux_ui->GetNativeTheme();
     if (native_theme)
       return native_theme;
   }
 
   return ui::NativeTheme::instance();
 }
 
 }  // namespace views