Remove closing method from KeyboardView

This is a follow up of Ie00ba827. After the change, the
KeyboardView.closing() method does nothing important.

Change-Id: I9659ea56ce82a95f8798a4136bf93f164b67fae7

java/src/com/android/inputmethod/keyboard/KeyboardView.java

@@ -635,15 +635,9 @@ public class KeyboardView extends View {
         invalidate(x, y, x + key.mWidth, y + key.mHeight);
     }
 
-    // TODO: Remove this method.
-    public void closing() {
-        mInvalidateAllKeys = true;
-    }
-
     @Override
     protected void onDetachedFromWindow() {
         super.onDetachedFromWindow();
-        closing();
         freeOffscreenBuffer();
     }
 }

java/src/com/android/inputmethod/keyboard/MainKeyboardView.java

@@ -1236,13 +1236,11 @@ public final class MainKeyboardView extends KeyboardView implements PointerTrack
         mDrawingHandler.cancelAllMessages();
     }
 
-    @Override
     public void closing() {
         dismissAllKeyPreviews();
         cancelAllMessages();
         onDismissMoreKeysPanel();
         mMoreKeysKeyboardCache.clear();
-        super.closing();
     }
 
     /**

java/src/com/android/inputmethod/keyboard/MoreKeysKeyboardView.java

@@ -174,7 +174,6 @@ public class MoreKeysKeyboardView extends KeyboardView implements MoreKeysPanel
 
     @Override
     public boolean dismissMoreKeysPanel() {
-        super.closing();
         if (mController == null) return false;
         return mController.onDismissMoreKeysPanel();
     }