Send a message from WebViewImpl to the compositor to inform about end of flings
https://bugs.webkit.org/show_bug.cgi?id=104947

Patch by Yusuf Ozuysal <yusufo@google.com> on 2012-12-14
Reviewed by James Robinson.

Whenever we have a fling animation finished on cancelled on main thread this sends
a message that will be relayed to the compositor input handler. Then the input handler
keeps track of main thread fling with a boolean and doesn't send flingCancels
unnecessarily

* chromium/public/WebInputHandler.h:
(WebInputHandler):
* chromium/public/WebLayerTreeView.h:
(WebLayerTreeView):
(WebKit::WebLayerTreeView::mainThreadHasStoppedFlinging):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk/Source/Platform/chromium/public@137793 268f45cc-cd09-0410-ab3c-d52691b4dbfc