Add histograms for MouseEventPrefetch.Tap* and fix wrong enum description for MouseEventFollowedByClick.

This is continuation of: https://codereview.chromium.org/15027003/

BUG=234036
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/14652033

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@200135 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed