Add pref entry for virtual keyboard

chrome/browser/chromeos/input_method/virtual_keyboard_selector.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_CHROMEOS_INPUT_METHOD_VIRTUAL_KEYBOARD_SELECTOR_H_
 #define CHROME_BROWSER_CHROMEOS_INPUT_METHOD_VIRTUAL_KEYBOARD_SELECTOR_H_
 #pragma once
 
 #include <list>
 #include <map>
@@ skipping 73 matching lines @@
   // Sets user preferences on virtual keyboard selection so that the virtual
   // keyboard extension specified by the |url| is always selected for the
   // |layout|. Returns false if a virtual keyboard extension whose address is
   // |url| is not registered, or the extension specified by the |url| does not
   // support the |layout|.
   bool SetUserPreference(const std::string& layout, const GURL& url);
 
   // Removes the preference for the |layout| added by SetUserPreference.
   void RemoveUserPreference(const std::string& layout);
 
+  // Removes all preferences added by SetUserPreference.
+  void ClearUserPreference();
+
  protected:
   // Selects and returns the most suitable virtual keyboard extension for the
   // |layout|. Unlike SelectVirtualKeyboard(), this function only scans
   // |keyboards_| and |system_keyboards_| (in this order), and never updates
   // |current_|. The function is protected for testability.
   const VirtualKeyboard* SelectVirtualKeyboardWithoutPreferences(
       const std::string& layout);
 
  private:
   // A list of third party virtual keyboard extensions.
@@ skipping 10 matching lines @@
   // The virtual keyboard currently in use.
   const VirtualKeyboard* current_;
 
   DISALLOW_COPY_AND_ASSIGN(VirtualKeyboardSelector);
 };
 
 }  // namespace input_method
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_INPUT_METHOD_VIRTUAL_KEYBOARD_SELECTOR_H_