Use the pinch viewport offset for tap disambiguation.

Source/web/tests/WebFrameTest.cpp

 /*
  * Copyright (C) 2010 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 4113 matching lines @@
 
     frame = webViewHelper.webView()->mainFrame();
     frame->executeCommand(WebString::fromUTF8("Unselect"));
     webViewHelper.webView()->layout();
     ASSERT_FALSE(frame->hasSelection());
     EXPECT_TRUE(fakeSelectionLayerTreeView.getAndResetSelectionCleared());
 }
 
 class DisambiguationPopupTestWebViewClient : public FrameTestHelpers::TestWebViewClient {
 public:
-    virtual bool didTapMultipleTargets(const WebGestureEvent&, const WebVector<WebRect>& targetRects) OVERRIDE
+    virtual bool didTapMultipleTargets(const WebSize&, const WebRect&, const WebVector<WebRect>& targetRects) OVERRIDE
     {
         EXPECT_GE(targetRects.size(), 2u);
         m_triggered = true;
         return true;
     }
 
     bool triggered() const { return m_triggered; }
     void resetTriggered() { m_triggered = false; }
     bool m_triggered;
 };
@@ skipping 2123 matching lines @@
     EXPECT_EQ(1u, frameClient.navigationalDataReceivedCount());
 
     // Neither should a page reload.
     localFrame->reload();
     EXPECT_EQ(4u, frameClient.provisionalLoadCount());
     EXPECT_FALSE(frameClient.wasLastProvisionalLoadATransition());
     EXPECT_EQ(1u, frameClient.navigationalDataReceivedCount());
 }
 
 } // namespace