[Mac] In BrowserWindowCocoa::Close() do not use -[NSWindow performClose:].

chrome/browser/ui/cocoa/browser_window_cocoa.mm

 // 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 "chrome/browser/ui/cocoa/browser_window_cocoa.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
@@ skipping 152 matching lines @@
 // Callers assume that this doesn't immediately delete the Browser object.
 // The controller implementing the window delegate methods called from
 // |-performClose:| must take precautions to ensure that.
 void BrowserWindowCocoa::Close() {
   // If there is an overlay window, we contain a tab being dragged between
   // windows. Don't hide the window as it makes the UI extra confused. We can
   // still close the window, as that will happen when the drag completes.
   if ([controller_ overlayWindow]) {
     [controller_ deferPerformClose];
   } else {
-    [window() performClose:controller_];
+    // Using |-performClose:| can prevent the window from actually closing if
+    // a JavaScript beforeunload handler opens an alert during shutdown, as
+    // documented at <http://crbug.com/118424>. Re-implement
+    // -[NSWindow performClose:] as closely as possible to how Apple documents
+    // it.
+    id<NSWindowDelegate> delegate = [window() delegate];
+    SEL window_should_close = @selector(windowShouldClose:);
+    if ([delegate respondsToSelector:window_should_close]) {
+      if ([delegate windowShouldClose:window()])
+        [window() close];
+    } else if ([window() respondsToSelector:window_should_close]) {
+      if ([window() performSelector:window_should_close withObject:window()])
+        [window() close];
+    } else {
+      [window() close];
+    }
   }
 }
 
 void BrowserWindowCocoa::Activate() {
   [controller_ activate];
 }
 
 void BrowserWindowCocoa::Deactivate() {
   // TODO(jcivelli): http://crbug.com/51364 Implement me.
   NOTIMPLEMENTED();
@@ skipping 471 matching lines @@
   AvatarMenuBubbleController* menu =
       [[AvatarMenuBubbleController alloc] initWithBrowser:browser_
                                                anchoredAt:point];
   [[menu bubble] setAlignment:info_bubble::kAlignEdgeToAnchorEdge];
   [menu showWindow:nil];
 }
 
 void BrowserWindowCocoa::ShowAvatarBubbleFromAvatarButton() {
   [[controller_ avatarButtonController] showAvatarBubble];
 }