[Mac] Tear down extension-installed bubble before main window closes.

chrome/browser/ui/cocoa/extensions/extension_popup_controller.mm

 // Copyright (c) 2011 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/extensions/extension_popup_controller.h"
 
 #include <algorithm>
 
 #include "chrome/browser/debugger/devtools_window.h"
 #include "chrome/browser/extensions/extension_host.h"
@@ skipping 153 matching lines @@
   NSWindow* window = [self window];
   DCHECK_EQ([notification object], window);
   // If the window isn't visible, it is already closed, and this notification
   // has been sent as part of the closing operation, so no need to close.
   if ([window isVisible] && !beingInspected_) {
     [self close];
   }
 }
 
 - (void)close {
-  [parentWindow_ removeChildWindow:[self window]];
-
-  // No longer have a parent window, so nil out the pointer and deregister for
-  // notifications.
-  NSNotificationCenter* center = [NSNotificationCenter defaultCenter];
-  [center removeObserver:self
-                    name:NSWindowWillCloseNotification
-                  object:parentWindow_];
-  parentWindow_ = nil;
+  [[[self window] parentWindow] removeChildWindow:[self window]];
   [super close];
 }
 
 - (BOOL)isClosing {
   return [static_cast<InfoBubbleWindow*>([self window]) isClosing];
 }
 
 - (ExtensionHost*)extensionHost {
   return host_.get();
 }
@@ skipping 137 matching lines @@
   return minSize;
 }
 
 // Private (TestingAPI)
 + (NSSize)maxPopupSize {
   NSSize maxSize = {ExtensionViewMac::kMaxWidth, ExtensionViewMac::kMaxHeight};
   return maxSize;
 }
 
 @end