Get Chrome version and store in cache & json files.

This updates crosperf to query the DUT for the version of Chrome
running on it, and to store the Chrome version both in the json
reports and in the human-readable cache keys file.

BUG=None
TEST=None

Change-Id: Ie8215528b8119f95306cad694e6898cc4810730e
Reviewed-on: https://chrome-internal-review.googlesource.com/230537
Commit-Ready: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
Reviewed-by: Han Shen <shenhan@google.com>
5 files changed