Delayed loading of the virtual keyboard.

ui/base/ime/input_method_observer.h

 // Copyright (c) 2013 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 UI_BASE_IME_INPUT_METHOD_OBSERVER_H_
 #define UI_BASE_IME_INPUT_METHOD_OBSERVER_H_
 
 #include "ui/base/ui_export.h"
 
 namespace ui {
 
+class InputMethod;
 class TextInputClient;
 
 class UI_EXPORT InputMethodObserver {
  public:
   virtual ~InputMethodObserver() {}
 
   // Called when either:
   //  - the TextInputClient is changed (e.g. by a change of focus)
   //  - the TextInputType of the TextInputClient changes
   virtual void OnTextInputStateChanged(const TextInputClient* client) = 0;
+
+  // Called when the observed InputMethod is being destroyed.
+  virtual void OnInputMethodDestroyed(const InputMethod* input_method) = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_IME_INPUT_METHOD_OBSERVER_H_