Improve WebValidationMessageClient interface and implementation.

public/webpage/WebValidationMessageClient.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 26 matching lines @@
 
 class WebString;
 struct WebRect;
 
 // Client interface to handle form validation message UI.
 class WebValidationMessageClient {
 public:
     // Show a notification popup for the specified form vaidation messages
     // besides the anchor rectangle. An implementation of this function should
     // not hide the popup until hideValidationMessage call.
-    virtual void showValidationMessage(const WebRect& anchorInScreen, const WebString& mainText, const WebString& supplementalText, WebTextDirection hint) { }
+    virtual void showValidationMessage(const WebRect& anchorInRootView, const WebString& mainText, const WebString& supplementalText, WebTextDirection hint) { }
 
     // Hide notifation popup for form validation messages.
     virtual void hideValidationMessage() { }
 
+    // Move the existing notifation popup for the new anchor position.
+    virtual void moveValidationMessage(const WebRect& anchorInRootView) { }
 
 protected:
     virtual ~WebValidationMessageClient() { }
 };
 
 } // namespace WebKit
 
 #endif