[chromium] Make WebLayerTreeView::adjustEventPointForPinchZoom pure virtual.
https://bugs.webkit.org/show_bug.cgi?id=100875

Reviewed by James Robinson.

This CL removes the default implementation for adjustEventPointForPinchZoom(), which
was necessary for landing the original patch in https://bugs.webkit.org/show_bug.cgi?id=100542.

* chromium/public/WebLayerTreeView.h:
(WebLayerTreeView):


git-svn-id: https://svn.webkit.org/repository/webkit/trunk/Source/Platform/chromium/public@133185 268f45cc-cd09-0410-ab3c-d52691b4dbfc