Fix the issue that GetFrameWindow() may change between AddObserver and RemoveObserver in KeyboardCo…

ui/keyboard/keyboard_controller.h

Index: ui/keyboard/keyboard_controller.h
diff --git a/ui/keyboard/keyboard_controller.h b/ui/keyboard/keyboard_controller.h
index 492a0ca00650981f9f7e3600cec9c34008cdbe78..55b67934af87d34a8e95551aeafee4e309deec62 100644
--- a/ui/keyboard/keyboard_controller.h
+++ b/ui/keyboard/keyboard_controller.h
@@ -139,11 +139,10 @@ class KEYBOARD_EXPORT KeyboardController : public ui::InputMethodObserver,
   void ShowAnimationFinished();
   void HideAnimationFinished();
 
-  // Adds or removes an observer for tracking changes to a window size or
+  // Adds an observer for tracking changes to a window size or
   // position while the keyboard is displayed. Any window repositioning
   // invalidates insets for overscrolling.
   void AddBoundsChangedObserver(aura::Window* window);
-  void RemoveBoundsChangedObserver(aura::Window* window);
 
   scoped_ptr<KeyboardControllerProxy> proxy_;
   scoped_ptr<aura::Window> container_;