Address a crash under -[NSWindow close] via a WeakPtr PostTask from Browser::TabStripEmpty()

chrome/browser/ui/cocoa/browser_window_controller.mm

 // Copyright 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.
 
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
 
 #include <cmath>
 #include <numeric>
 #include <utility>
 
@@ skipping 512 matching lines @@
              afterDelay:0];
 }
 
 // Called when the window meets the criteria to be closed (ie,
 // |-windowShouldClose:| returns YES). We must be careful to preserve the
 // semantics of BrowserWindow::Close() and not call the Browser's dtor directly
 // from this method.
 - (void)windowWillClose:(NSNotification*)notification {
   DCHECK_EQ([notification object], [self window]);
   DCHECK(browser_->tab_strip_model()->empty());
+  windowShim_->OnWindowWillClose();
   [savedRegularWindow_ close];
   // We delete statusBubble here because we need to kill off the dependency
   // that its window has on our window before our window goes away.
   delete statusBubble_;
   statusBubble_ = NULL;
   // We can't actually use |-autorelease| here because there's an embedded
   // run loop in the |-performClose:| which contains its own autorelease pool.
   // Instead call it after a zero-length delay, which gets us back to the main
   // event loop.
   [self performSelector:@selector(autorelease)
@@ skipping 1513 matching lines @@
 
 - (BOOL)isTabbedWindow {
   return browser_->is_type_tabbed();
 }
 
 - (NSRect)savedRegularWindowFrame {
   return savedRegularWindowFrame_;
 }
 
 @end  // @implementation BrowserWindowController(WindowType)