Make a clean interface for dialog callbacks.

chrome/browser/ui/app_modal_dialogs/app_modal_dialog_queue.h

 // Copyright (c) 2010 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_APP_MODAL_DIALOGS_APP_MODAL_DIALOG_QUEUE_H_
 #define CHROME_BROWSER_UI_APP_MODAL_DIALOGS_APP_MODAL_DIALOG_QUEUE_H_
 #pragma once
 
-#include <queue>
+#include <deque>
 
 #include "chrome/browser/ui/app_modal_dialogs/app_modal_dialog.h"
 
 template <typename T> struct DefaultSingletonTraits;
 
 // Keeps a queue of AppModalDialogs, making sure only one app modal
 // dialog is shown at a time.
 // This class is a singleton.
 class AppModalDialogQueue {
  public:
@@ skipping 29 matching lines @@
   // Returns true if there is currently an active app modal dialog box.
   bool HasActiveDialog() {
     return active_dialog_ != NULL;
   }
 
   // Accessor for |active_dialog_|.
   AppModalDialog* active_dialog() {
     return active_dialog_;
   }
 
+  // Iterators to walk the queue.
+  typedef std::deque<AppModalDialog*>::iterator iterator;
+  iterator begin() {
+    return app_modal_dialog_queue_.begin();
+  }
+
+  iterator end() {
+    return app_modal_dialog_queue_.end();
+  }
+
  private:
   friend struct DefaultSingletonTraits<AppModalDialogQueue>;
 
   AppModalDialogQueue();
   ~AppModalDialogQueue();
 
   // Shows |dialog| and notifies the BrowserList that a modal dialog is showing.
   void ShowModalDialog(AppModalDialog* dialog);
 
   // Returns the next dialog to show. This removes entries from
   // app_modal_dialog_queue_ until one is valid or the queue is empty. This
   // returns NULL if there are no more dialogs, or all the dialogs in the queue
   // are not valid.
   AppModalDialog* GetNextDialog();
 
   // Contains all app modal dialogs which are waiting to be shown, with the
   // currently modal dialog at the front of the queue.
-  std::queue<AppModalDialog*> app_modal_dialog_queue_;
+  std::deque<AppModalDialog*> app_modal_dialog_queue_;
 
   // The currently active app-modal dialog box's delegate. NULL if there is no
   // active app-modal dialog box.
   AppModalDialog* active_dialog_;
 
   // Stores if |ShowModalDialog()| is currently being called on an app-modal
   // dialog.
   bool showing_modal_dialog_;
 
   DISALLOW_COPY_AND_ASSIGN(AppModalDialogQueue);
 };
 
 #endif  // CHROME_BROWSER_UI_APP_MODAL_DIALOGS_APP_MODAL_DIALOG_QUEUE_H_