Add pref entry for virtual keyboard

chrome/browser/chromeos/input_method/virtual_keyboard_selector.cc

 // 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.
 
 #include "chrome/browser/chromeos/input_method/virtual_keyboard_selector.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 
 namespace {
@@ skipping 127 matching lines @@
 
   RemoveUserPreference(layout);
   user_preference_.insert(std::make_pair(layout, keyboard));
   return true;
 }
 
 void VirtualKeyboardSelector::RemoveUserPreference(const std::string& layout) {
   user_preference_.erase(layout);
 }
 
+void VirtualKeyboardSelector::ClearAllUserPreferences() {
+  user_preference_.clear();
+}
+
 const VirtualKeyboard*
 VirtualKeyboardSelector::SelectVirtualKeyboardWithoutPreferences(
     const std::string& layout) {
   const VirtualKeyboard* keyboard =
       SelectVirtualKeyboardInternal(keyboards_, layout);
   if (!keyboard)
     keyboard = SelectVirtualKeyboardInternal(system_keyboards_, layout);
   return keyboard;
 }
 
 }  // namespace input_method
 }  // namespace chromeos