Make keyboard controller a singleton.

ash/system/chromeos/virtual_keyboard/virtual_keyboard_tray.cc

 // Copyright 2014 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 "ash/system/chromeos/virtual_keyboard/virtual_keyboard_tray.h"
 
 #include "ash/shell.h"
 #include "ash/system/status_area_widget.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "ash/system/tray/tray_constants.h"
@@ skipping 80 matching lines @@
 
 void VirtualKeyboardTray::HideBubbleWithView(
     const views::TrayBubbleView* bubble_view) {
 }
 
 bool VirtualKeyboardTray::ClickedOutsideBubble() {
   return false;
 }
 
 bool VirtualKeyboardTray::PerformAction(const ui::Event& event) {
-  Shell::GetInstance()->keyboard_controller()->ShowAndLockKeyboard();
+  keyboard::KeyboardController::GetInstance()->ShowAndLockKeyboard();
   return true;
 }
 
 void VirtualKeyboardTray::ButtonPressed(views::Button* sender,
                                         const ui::Event& event) {
   DCHECK_EQ(button_, sender);
   PerformAction(event);
 }
 
 void VirtualKeyboardTray::OnAccessibilityModeChanged(
     AccessibilityNotificationVisibility notify) {
   SetVisible(Shell::GetInstance()->accessibility_delegate()->
       IsVirtualKeyboardEnabled());
 }
 
 }  // namespace ash