Use the pinch viewport offset for tap disambiguation.

public/web/WebViewClient.h

 /*
  * Copyright (C) 2009 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 186 matching lines @@
     // Called when a new node gets focused.
     virtual void focusedNodeChanged(const WebNode&) { }
 
     // Indicates two things:
     //   1) This view may have a new layout now.
     //   2) Calling layout() is a no-op.
     // After calling WebWidget::layout(), expect to get this notification
     // unless the view did not need a layout.
     virtual void didUpdateLayout() { }
 
+    // FIXME: This is a deprecated method. Remove it after the chromium change
+    // that uses the second didTapMultipleTargets() propagates.
+    //
     // Return true to swallow the input event if the embedder will start a disambiguation popup
     virtual bool didTapMultipleTargets(const WebGestureEvent&, const WebVector<WebRect>& targetRects) { return false; }
 
+    // Return true to swallow the input event if the embedder will start a disambiguation popup
+    virtual bool didTapMultipleTargets(const WebSize& pinchViewportOffset, const WebRect& touchRect, const WebVector<WebRect>& targetRects) { return false; }
+
     // Returns comma separated list of accept languages.
     virtual WebString acceptLanguages() { return WebString(); }
 
 
     // Session history -----------------------------------------------------
 
     // Tells the embedder to navigate back or forward in session history by
     // the given offset (relative to the current position in session
     // history).
     virtual void navigateBackForwardSoon(int offset) { }
@@ skipping 86 matching lines @@
     // Informs the browser that the draggable regions have been updated.
     virtual void draggableRegionsChanged() { }
 
 protected:
     ~WebViewClient() { }
 };
 
 } // namespace blink
 
 #endif