[Aura] Polish app list.

chrome/browser/ui/webui/aura/app_list_ui.h

 // Copyright (c) 2011 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_WEBUI_AURA_APP_LIST_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_AURA_APP_LIST_UI_H_
 #pragma once
 
 #include "chrome/browser/ui/webui/chrome_web_ui.h"
 
+class AppListUIDelegate;
+
 class AppListUI : public ChromeWebUI {
  public:
   explicit AppListUI(TabContents* contents);
 
+  AppListUIDelegate* delegate() const {
+    return delegate_;
+  }
+
+  void set_delegate(AppListUIDelegate* delegate) {
+    delegate_ = delegate;
+  }
+
  private:
+  AppListUIDelegate* delegate_;
+
   DISALLOW_COPY_AND_ASSIGN(AppListUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_AURA_APP_LIST_UI_H_