Cleanup: remove redundant tab close observation from TabModalConfirmDialogDelegate

chrome/browser/ui/cocoa/constrained_window/constrained_window_mac.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/constrained_window/constrained_window_mac.h"
 
 #include "base/logging.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_window.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_sheet_controller.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
 #include "components/web_modal/web_contents_modal_dialog_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_view.h"
 
 using web_modal::WebContentsModalDialogManager;
 using web_modal::NativeWebContentsModalDialog;
 
 ConstrainedWindowMac::ConstrainedWindowMac(
     ConstrainedWindowMacDelegate* delegate,
     content::WebContents* web_contents,
     id<ConstrainedWindowSheet> sheet)
     : delegate_(delegate),
       web_contents_(web_contents),
       sheet_([sheet retain]),
-      shown_(false) {
+      shown_(false),
+      closing_(false) {
   DCHECK(web_contents);
   DCHECK(sheet_.get());
   WebContentsModalDialogManager* web_contents_modal_dialog_manager =
       WebContentsModalDialogManager::FromWebContents(web_contents);
   web_contents_modal_dialog_manager->ShowDialog(this);
 }
 
 ConstrainedWindowMac::~ConstrainedWindowMac() {
   CHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 }
 
 void ConstrainedWindowMac::ShowWebContentsModalDialog() {
   if (shown_)
     return;
 
   NSWindow* parent_window = GetParentWindow();
   NSView* parent_view = GetSheetParentViewForWebContents(web_contents_);
   if (!parent_window || !parent_view)
     return;
 
   shown_ = true;
   ConstrainedWindowSheetController* controller =
       [ConstrainedWindowSheetController
           controllerForParentWindow:parent_window];
   [controller showSheet:sheet_ forParentView:parent_view];
 }
 
 void ConstrainedWindowMac::CloseWebContentsModalDialog() {
+  if (closing_)
+    return;
+
+  closing_ = true;
   [[ConstrainedWindowSheetController controllerForSheet:sheet_]
       closeSheet:sheet_];
   WebContentsModalDialogManager* web_contents_modal_dialog_manager =
       WebContentsModalDialogManager::FromWebContents(web_contents_);
   web_contents_modal_dialog_manager->WillClose(this);
   if (delegate_)
     delegate_->OnConstrainedWindowClosed(this);
 }
 
 void ConstrainedWindowMac::FocusWebContentsModalDialog() {
@@ skipping 21 matching lines @@
 
 NSWindow* ConstrainedWindowMac::GetParentWindow() const {
   // Tab contents in a tabbed browser may not be inside a window. For this
   // reason use a browser window if possible.
   Browser* browser = chrome::FindBrowserWithWebContents(web_contents_);
   if (browser)
     return browser->window()->GetNativeWindow();
 
   return web_contents_->GetView()->GetTopLevelNativeWindow();
 }