PyAuto: fix extra flags passed to chrome
PyAuto: fix extra flags passed to chrome

1. Fix so that extra flags passed actually get passed on to chrome
2. Make it easier (get rid of --ui-test-flags option since it was cumbersome)
  Now, extra options can be passed like:
  python mytest.py --chrome-flags="--enable-crash-reporter"

Still need a way for an individual TestCase to be able to add flags, without
being provided from the command line.

Review URL: http://codereview.chromium.org/2833015

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@50170 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser