Added usage of ScreenContext in EulaScreen.

chrome/browser/chromeos/login/screens/base_screen.h

 // Copyright (c) 2012 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_CHROMEOS_LOGIN_SCREENS_BASE_SCREEN_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_BASE_SCREEN_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 64 matching lines @@
 
  protected:
   // Screen can call this method to notify framework that it have finished
   // it's work with |outcome|.
   void Finish(BaseScreenDelegate::ExitCodes exit_code);
 
   // Called when button with |button_id| was pressed. Notification
   // about this event comes from the JS counterpart.
   virtual void OnButtonPressed(const std::string& button_id);
 
-  // Called when context for the currenct screen was
-  // changed. Notification about this event comes from the JS
-  // counterpart.
-  virtual void OnContextChanged(const base::DictionaryValue* diff);
+  // The method is called each time some key in screen context is
+  // updated by JS side. Default implementation does nothing, so
+  // subclasses should override it in order to observe updates in
+  // screen context.
+  virtual void OnContextKeyUpdated(const ::login::ScreenContext::KeyType& key);
 
   BaseScreenDelegate* get_base_screen_delegate() const {
     return base_screen_delegate_;
   }
 
   ::login::ScreenContext context_;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(EnrollmentScreenTest, TestCancel);
   FRIEND_TEST_ALL_PREFIXES(EnrollmentScreenTest, TestSuccess);
   FRIEND_TEST_ALL_PREFIXES(ProvisionedEnrollmentScreenTest, TestBackButton);
 
+  friend class BaseScreenHandler;
   friend class NetworkScreenTest;
   friend class ScreenManager;
   friend class UpdateScreenTest;
 
   void SetContext(::login::ScreenContext* context);
 
+  // Called when context for the current screen was
+  // changed. Notification about this event comes from the JS
+  // counterpart.
+  void OnContextChanged(const base::DictionaryValue& diff);
+
   BaseScreenDelegate* base_screen_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(BaseScreen);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_BASE_SCREEN_H_