Make Mandoline shut down cleanly.

ui/platform_window/x11/x11_window.cc

 // Copyright 2014 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/platform_window/x11/x11_window.h"
 
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
@@ skipping 28 matching lines @@
 }
 
 }  // namespace
 
 X11Window::X11Window(PlatformWindowDelegate* delegate)
     : delegate_(delegate),
       xdisplay_(gfx::GetXDisplay()),
       xwindow_(None),
       xroot_window_(DefaultRootWindow(xdisplay_)),
       atom_cache_(xdisplay_, kAtomsToCache),
-      window_mapped_(false) {
+      window_mapped_(false),
+      destroyed_(false) {
   CHECK(delegate_);
   TouchFactory::SetTouchDeviceListFromCommandLine();
 }
 
 X11Window::~X11Window() {
   Destroy();
 }
 
 void X11Window::Destroy() {
-  delegate_->OnClosed();
-  if (xwindow_ == None)
+  if (destroyed_)
     return;
 
-  // Stop processing events.
-  PlatformEventSource::GetInstance()->RemovePlatformEventDispatcher(this);
-  XDestroyWindow(xdisplay_, xwindow_);
-  xwindow_ = None;
+  destroyed_ = true;
+
+  if (xwindow_ != None) {
+    // Stop processing events.
+    PlatformEventSource::GetInstance()->RemovePlatformEventDispatcher(this);
+    XDestroyWindow(xdisplay_, xwindow_);
+    xwindow_ = None;
+  }
+
+  delegate_->OnClosed();
+  // |this| could be deleted now.
 }
 
 void X11Window::ProcessXInput2Event(XEvent* xev) {
   if (!TouchFactory::GetInstance()->ShouldProcessXI2Event(xev))
     return;
   EventType event_type = EventTypeFromNative(xev);
   switch (event_type) {
     case ET_KEY_PRESSED:
     case ET_KEY_RELEASED: {
       KeyEvent key_event(xev);
@@ skipping 278 matching lines @@
 
     case GenericEvent: {
       ProcessXInput2Event(xev);
       break;
     }
   }
   return POST_DISPATCH_STOP_PROPAGATION;
 }
 
 }  // namespace ui