Support 3f swipe for tab scrubbing

Tests will be added if we like approach and take out from behind
flag.

BUG=124830
TEST=None

Review URL: https://codereview.chromium.org/11411247

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170138 0039d316-1c4b-4281-b951-d872f2087c98
7 files changed