Do not show a tooltip same as the previous one.

third_party/WebKit/Source/core/page/ChromeClient.cpp

 /*
  * Copyright (C) 2006, 2007, 2009, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2012, Samsung Electronics. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 149 matching lines @@
                 // FIXME: We should obtain text direction of tooltip from
                 // ChromeClient or platform. As of October 2011, all client
                 // implementations don't use text direction information for
                 // ChromeClient::setToolTip. We'll work on tooltip text
                 // direction during bidi cleanup in form inputs.
                 toolTipDirection = LTR;
             }
         }
     }
 
+    if (m_lastToolTipPoint == result.hitTestLocation().point() && m_lastToolTipText == toolTip)
+        return;
+    m_lastToolTipPoint = result.hitTestLocation().point();
+    m_lastToolTipText = toolTip;
     setToolTip(toolTip, toolTipDirection);
 }
 
+void ChromeClient::clearToolTip()
+{
+    // Do not check m_lastToolTip* and do not update them intentionally.
+    // We don't want to show tooltips with same content after clearToolTip().
+    setToolTip(String(), LTR);
+}
+
 void ChromeClient::print(LocalFrame* frame)
 {
     // Defer loads in case the client method runs a new event loop that would
     // otherwise cause the load to continue while we're in the middle of
     // executing JavaScript.
     ScopedPageLoadDeferrer deferrer;
 
     printDelegate(frame);
 }
 
 } // namespace blink