GitLab

Allow notifications of unhandled taps via the GestureStateListener.  This change
makes GestureTap events blocking, but there are several use-cases for which this
will be necessary, e.g., WebView and contextual search.

NOTRY=true

Review URL: https://codereview.chromium.org/218633008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261431 0039d316-1c4b-4281-b951-d872f2087c98