[chromedriver] Generate mobile devices list from OverridesUI.js.

BUG=chromedriver:843
TBR=stgao@chromium.org

Review URL: https://codereview.chromium.org/385753002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282477 0039d316-1c4b-4281-b951-d872f2087c98