GitLab

This allows touch devices to be grabbed when events from the mouse/keyboard are
grabbed. This also exposes TouchFactory, which will eventually be used in more
places.

BUG=none
TEST=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=71879

Review URL: http://codereview.chromium.org/6300007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@72002 0039d316-1c4b-4281-b951-d872f2087c98