Linux: don't crash when closing tabs that have open login prompts.

chrome/browser/login_prompt_gtk.cc

 // Copyright (c) 2009 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/login_prompt.h"
 
 #include <gtk/gtk.h>
 
 #include "app/l10n_util.h"
 #include "base/message_loop.h"
@@ skipping 41 matching lines @@
     }
   }
 
   virtual ~LoginHandlerGtk() {
     if (login_model_)
       login_model_->SetObserver(NULL);
     root_.Destroy();
   }
 
   void SetModel(LoginModel* model) {
+    if (login_model_)
+      login_model_->SetObserver(NULL);
     login_model_ = model;
     if (login_model_)
       login_model_->SetObserver(this);
   }
 
   // LoginModelObserver implementation.
   virtual void OnAutofillDataAvailable(const std::wstring& username,
                                        const std::wstring& password) {
     // NOTE: Would be nice to use gtk_entry_get_text_length, but it is fairly
     // new and not always in our GTK version.
@@ skipping 127 matching lines @@
   }
 
   virtual void DeleteDelegate() {
     if (!WasAuthHandled(true)) {
       request_loop_->PostTask(FROM_HERE, NewRunnableMethod(
           this, &LoginHandlerGtk::CancelAuthDeferred));
       ui_loop_->PostTask(FROM_HERE, NewRunnableMethod(
           this, &LoginHandlerGtk::SendNotifications));
     }
 
+    SetModel(NULL);
+
     // Delete this object once all InvokeLaters have been called.
     request_loop_->ReleaseSoon(FROM_HERE, this);
   }
 
  private:
   friend class LoginPrompt;
 
   // Calls SetAuth from the request_loop.
   void SetAuthDeferred(const std::wstring& username,
                        const std::wstring& password) {
@@ skipping 118 matching lines @@
   // so it doesn't try and access this when its too late.
   LoginModel* login_model_;
 
   DISALLOW_COPY_AND_ASSIGN(LoginHandlerGtk);
 };
 
 // static
 LoginHandler* LoginHandler::Create(URLRequest* request, MessageLoop* ui_loop) {
   return new LoginHandlerGtk(request, ui_loop);
 }