Makes sure that an input method doesn't reference to a destroyed object.

ui/base/ime/input_method_base.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 UI_BASE_IME_INPUT_METHOD_BASE_H_
 #define UI_BASE_IME_INPUT_METHOD_BASE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/observer_list.h"
@@ skipping 19 matching lines @@
 
   // Overriden from InputMethod.
   virtual void SetDelegate(internal::InputMethodDelegate* delegate) OVERRIDE;
   virtual void Init(bool focused) OVERRIDE;
   // If a derived class overrides OnFocus()/OnBlur(), it should call parent's
   // implementation first, to make sure |system_toplevel_window_focused_| flag
   // can be updated correctly.
   virtual void OnFocus() OVERRIDE;
   virtual void OnBlur() OVERRIDE;
   virtual void SetFocusedTextInputClient(TextInputClient* client) OVERRIDE;
+  virtual void DetachTextInputClient(TextInputClient* client) OVERRIDE;
   virtual TextInputClient* GetTextInputClient() const OVERRIDE;
 
   // If a derived class overrides this method, it should call parent's
   // implementation.
   virtual void OnTextInputTypeChanged(const TextInputClient* client) OVERRIDE;
 
   virtual TextInputType GetTextInputType() const OVERRIDE;
   virtual TextInputMode GetTextInputMode() const OVERRIDE;
   virtual bool CanComposeInline() const OVERRIDE;
 
@@ skipping 43 matching lines @@
   ObserverList<InputMethodObserver> observer_list_;
 
   bool system_toplevel_window_focused_;
 
   DISALLOW_COPY_AND_ASSIGN(InputMethodBase);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_IME_INPUT_METHOD_BASE_H_