content: Cleanup class/struct forward declarations

chrome/browser/ui/webui/app_launcher_login_handler.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_APP_LAUNCHER_LOGIN_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_APP_LAUNCHER_LOGIN_HANDLER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
 class Profile;
 class ProfileInfoWatcher;
 
+namespace base {
+class DictionaryValue;
+}
+
 // The login handler currently simply displays the current logged in
 // username at the top of the NTP (and update itself when that changes).
 // In the future it may expand to allow users to login from the NTP.
 class AppLauncherLoginHandler : public content::WebUIMessageHandler {
  public:
   AppLauncherLoginHandler();
   ~AppLauncherLoginHandler() override;
 
   // WebUIMessageHandler implementation:
   void RegisterMessages() override;
@@ skipping 39 matching lines @@
   void UpdateLogin();
 
   // Watches this web UI's profile for info changes (e.g. authenticated username
   // changes).
   std::unique_ptr<ProfileInfoWatcher> profile_info_watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(AppLauncherLoginHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_APP_LAUNCHER_LOGIN_HANDLER_H_