Don't try to use ManagePasswordsBubbleModel if the password bubble was closed.

chrome/browser/ui/cocoa/passwords/pending_password_view_controller.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_PASSWORDS_PENDING_PASSWORD_VIEW_CONTROLLER_H_
 #define CHROME_BROWSER_UI_COCOA_PASSWORDS_PENDING_PASSWORD_VIEW_CONTROLLER_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/passwords/base_passwords_content_view_controller.h"
 
-class ManagePasswordsBubbleModel;
 @class PasswordsListViewController;
 
 // Base class for the views that offer to save/update the user's password.
 @interface PendingPasswordViewController
     : ManagePasswordsBubbleContentViewController<NSTextViewDelegate> {
  @private
-  ManagePasswordsBubbleModel* model_;  // weak
   base::scoped_nsobject<NSButton> closeButton_;
 }
-- (id)initWithModel:(ManagePasswordsBubbleModel*)model
-           delegate:(id<ManagePasswordsBubbleContentViewDelegate>)delegate;
 
 // Creates a controller for showing username/password and returns its view.
 - (NSView*)createPasswordView;
 
 // Returns whether GoogleSmartLock warm welcome should be shown.
 - (BOOL)shouldShowGoogleSmartLockWelcome;
 
 // Creates buttons that should be shown in the bubble and returns them.
 - (NSArray*)createButtonsAndAddThemToView:(NSView*)view;
 
 @property(readonly) ManagePasswordsBubbleModel* model;
 @end
 
 @interface PendingPasswordViewController (Testing)
 @property(readonly) NSButton* closeButton;
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_PASSWORDS_PENDING_PASSWORD_VIEW_CONTROLLER_H_