Use the pinch viewport offset for tap disambiguation.

content/renderer/render_view_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_RENDER_VIEW_IMPL_H_
 #define CONTENT_RENDERER_RENDER_VIEW_IMPL_H_
 
 #include <deque>
 #include <map>
 #include <set>
@@ skipping 392 matching lines @@
                              blink::WebDragOperationsMask mask,
                              const blink::WebImage& image,
                              const blink::WebPoint& imageOffset);
   virtual bool acceptsLoadDrops();
   virtual void focusNext();
   virtual void focusPrevious();
   virtual void focusedNodeChanged(const blink::WebNode& node);
   virtual void didUpdateLayout();
 #if defined(OS_ANDROID)
   virtual bool didTapMultipleTargets(
-      const blink::WebGestureEvent& event,
+      const blink::WebSize& inner_viewport_offset,
+      const blink::WebRect& touch_rect,
       const blink::WebVector<blink::WebRect>& target_rects);
 #endif
   virtual blink::WebString acceptLanguages();
   virtual void navigateBackForwardSoon(int offset);
   virtual int historyBackListCount();
   virtual int historyForwardListCount();
   virtual blink::WebSpeechRecognizer* speechRecognizer();
   virtual void zoomLimitsChanged(double minimum_level, double maximum_level);
   virtual void zoomLevelChanged();
   virtual double zoomLevelToZoomFactor(double zoom_level) const;
@@ skipping 707 matching lines @@
   // use the Observer interface to filter IPC messages and receive frame change
   // notifications.
   // ---------------------------------------------------------------------------
 
   DISALLOW_COPY_AND_ASSIGN(RenderViewImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_VIEW_IMPL_H_