When gaia_login=False in chrome.Chrome() method, Chrome OS does not download policies from the --device-management-url specified by the user in extra_browser_args.

Workaround: If --device-management-url is specified in extra_browser_args, then set gaia_login=True. When login succeeds, policies will be downloaded from the specified DMS URL.

Steps to Reproduce:
1) Edit enterprise_policy_base.py so that gaia_login is always set False. Currently, the workaround above sets gaia_login=True when using a user-specified server, and False when using the default, Fake DM server.
2) Run test_that <IP> policy_EditBookmarksEnabled --args='case=False_Disabled env=dm-fake'. Note that policies are successfully downloaded (they appear on the chrome://policy page) from the Fake DM server.
3) Run test_that <IP> <policy_EditBookmarksEnabled --args='case=False_Disabled env=prod username=<valid_user> password=<valid_password>. Note that policies are not downloaded (the chrome://policy page is blank) when using the production DMS.

Expected: Policies should be downloaded from the specified DMS policy server when gaia_login is True or False.