Retrieve event flags from leave/notify event state

BUG=318827
TEST=manual. see bug for repro step

Review URL: https://codereview.chromium.org/114643004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241378 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241378
Stop scheduling fling updates when fling scrolling no longer possible

Save power by eliminating unnecessary fling scheduling after a fling has
overscrolled all axes for which it will generate scroll updates.

BUG=328520

Review URL: https://codereview.chromium.org/115513003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241379 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241379