[chromedriver] Add a python test to verify chromedriver.log is not empty.

BUG=chromedriver:638
NOTRY=true

Review URL: https://codereview.chromium.org/144303003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246192 0039d316-1c4b-4281-b951-d872f2087c98
[chromedriver] Remove downloaded chrome snapshots from /tmp.

BUG=None
R=chrisgao@chromium.org

Review URL: https://codereview.chromium.org/145153003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246679 0039d316-1c4b-4281-b951-d872f2087c98
[chromedriver] Fix run_all_tests.py broken by r246679

TBR=stgao@chromium.org
BUG=

Review URL: https://codereview.chromium.org/131903007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246722 0039d316-1c4b-4281-b951-d872f2087c98
[chromedriver] Fix the python test for chromedriver log.

BUG=None
NOTRY=True

Review URL: https://codereview.chromium.org/146133004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246723 0039d316-1c4b-4281-b951-d872f2087c98