Added usefull utility methods to Screen and ScreenContext.

chrome/browser/ui/webui/chromeos/login/base_screen_handler_utils.h

 // Copyright (c) 2013 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_CHROMEOS_LOGIN_BASE_SCREEN_HANDLER_UTILS_H_
 #define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_BASE_SCREEN_HANDLER_UTILS_H_
 
 #include <cstddef>
 #include <string>
 
@@ skipping 47 matching lines @@
 template<>
 inline bool ParseValue<const base::DictionaryValue*>(
     const base::Value* value,
     const base::DictionaryValue** out_value) {
   return value->GetAsDictionary(out_value);
 }
 
 template<typename T>
 inline bool GetArg(const base::ListValue* args, size_t index, T* out_value) {
   const base::Value* value;
-  if (!args->Get(index, &value))
+  if (!args->Get(index, &value)) {
+    LOG(ERROR) << "Returning false";

[ygorshenin1, 2014/06/11 10:44:00]

nit: debug code?

[dzhioev (left Google), 2014/06/18 14:43:39]

Yes. Removed.

     return false;
+  }
   return ParseValue(value, out_value);
 }
 
 inline base::FundamentalValue MakeValue(bool v) {
   return base::FundamentalValue(v);
 }
 
 inline base::FundamentalValue MakeValue(int v) {
   return base::FundamentalValue(v);
 }
@@ skipping 81 matching lines @@
       !GetArg(args, 3, &arg4)) {
     NOTREACHED();
     return;
   }
   callback.Run(arg1, arg2, arg3, arg4);
 }
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_BASE_SCREEN_HANDLER_UTILS_H_