Check Webdriver by starting a session.

The normal socket check is not enough.  The webservice may be running
but we may encounter another error.  Now we attempt to start a session.

BUG=chromium:263275
TEST=Manual, ran it

Change-Id: I8d675b09ac4da47d3956e7df39c546898fd73833
Reviewed-on: https://gerrit.chromium.org/gerrit/63370
Reviewed-by: Viral Modi <viralmodi@chromium.org>
Tested-by: Kris Rambish <krisr@chromium.org>
1 file changed