Use variadic template for screen handler's AddCallback.

components/webui_generator/web_ui_view.h

 // Copyright 2015 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_WUG_WEB_UI_VIEW_H_
 #define CHROME_BROWSER_UI_WEBUI_WUG_WEB_UI_VIEW_H_
 
 #include <string>
 
 #include "base/bind.h"
@@ skipping 40 matching lines @@
 
   // Overridden from View:
   void Init() override;
 
  protected:
   using ResourcesMap =
       base::hash_map<std::string, scoped_refptr<base::RefCountedMemory>>;
 
   content::WebUI* web_ui() { return web_ui_; }
 
-  template <typename T>
-  void AddCallback(const std::string& name, void (T::*method)()) {
-    base::Callback<void()> callback =
+  template <typename T, typename... Args>
+  void AddCallback(const std::string& name, void (T::*method)(Args...)) {
+    base::Callback<void(Args...)> callback =
         base::Bind(method, base::Unretained(static_cast<T*>(this)));
     web_ui_->RegisterMessageCallback(
-        name, base::Bind(&::login::CallbackWrapper0, callback));
-  }
-
-  template <typename T, typename A1>
-  void AddCallback(const std::string& name, void (T::*method)(A1 arg1)) {
-    base::Callback<void(A1)> callback =
-        base::Bind(method, base::Unretained(static_cast<T*>(this)));
-    web_ui_->RegisterMessageCallback(
-        name, base::Bind(&::login::CallbackWrapper1<A1>, callback));
+        name, base::Bind(&::login::CallbackWrapper<Args...>, callback));
   }
 
   // Overridden from View:
   void OnReady() override;
   void OnContextChanged(const base::DictionaryValue& diff) override;
 
   virtual void AddLocalizedValues(::login::LocalizedValuesBuilder* builder) = 0;
   virtual void AddResources(ResourcesMap* resources_map) = 0;
 
  private:
@@ skipping 22 matching lines @@
   bool html_ready_;
   bool view_bound_;
   scoped_ptr<Context> pending_context_changes_;
 
   DISALLOW_COPY_AND_ASSIGN(WebUIView);
 };
 
 }  // namespace webui_generator
 
 #endif  // CHROME_BROWSER_UI_WEBUI_WUG_WEB_UI_VIEW_H_