ash: Start/stop observing KeyboardController via ShellObserver

ash/common/shell_observer.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 ASH_COMMON_SHELL_OBSERVER_H_
 #define ASH_COMMON_SHELL_OBSERVER_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/login_status.h"
 
@@ skipping 49 matching lines @@
   // animate though.
   virtual void OnMaximizeModeStarted() {}
 
   // Called when the maximize mode is about to end.
   virtual void OnMaximizeModeEnding() {}
 
   // Called when the maximize mode has ended. Windows may still be
   // animating but have been restored.
   virtual void OnMaximizeModeEnded() {}
 
-  // Called when keyboard is activated/deactivated.
-  virtual void OnVirtualKeyboardStateChanged(bool activated) {}
+  // Called when keyboard is activated/deactivated in |root_window|.
+  virtual void OnVirtualKeyboardStateChanged(bool activated,
+                                             WmWindow* root_window) {}
 
   // Called at the end of Shell::Init.
   virtual void OnShellInitialized() {}
 
  protected:
   virtual ~ShellObserver() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELL_OBSERVER_H_