Comment 5 for bug 1074733

This is strange: Google is trying to authenticate you via plain http, and not secure http (https) as it should. Are you behind a proxy?
Because of security reasons, some time ago we decided to support only https (see bug 1037169); however, there is a way to allow using plain http as well, by reconfiguring the account using the terminal:

  sudo apt-get install account-plugin-tools
  account-console list

Find the numeric ID of the google account; let's suppose it's 1234, and substitute it in the following commands:

  account-console edit 1234 -s "as:auth/oauth2/web_server/AllowedSchemes=['https','http']"
  account-console edit 1234 -s "as:auth/oauth2/user_agent/AllowedSchemes=['https','http']"

Then, if you restart the session, it should work.