Add an alternative way to specify extra chrome flags via env for testing

This is to work around a problem where passed command line flags (thru pyauto flag --chrome-flags) will not take effect on win.

Review URL: http://codereview.chromium.org/7005007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@84939 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed