Struct: GoogleReferral
| Key | Field | Type | Description | Requiredness | Default value |
| 1 | q | string | The query terms requested by the user
| optional | |
| 2 | rank | i32 | The rank we were list at within the source, as indicated by the "cd" query
parameter.
| optional | |
| 3 | source | string | The type of referral this was. Currently this is just a string, and is likely to
change as we overhaul our google ved parsing
| optional | |
Where the referrer was google and they've provided additional information
on the query string, here is
that additional information.