It's kind of gray:
Privacy
One of the most persistent misunderstandings about Safe Browsing is the idea that the browser needs to send all visited URLs to Google in order to verify whether or not they are safe.
While this was an option in version 1 of the Safe Browsing protocol (as disclosed in their privacy policy at the time), support for this "enhanced mode" was removed in Firefox 3 and the version 1 server was decommissioned in late 2011 in favor of version 2 of the Safe Browsing API which doesn't offer this type of real-time lookup.
Google explicitly states that the information collected as part of operating the Safe Browsing service "is only used to flag malicious activity and is never used anywhere else at Google" and that "Safe Browsing requests won't be associated with your Google Account". In addition, Firefox adds a few privacy protections:
Query string parameters are stripped from URLs we check as part of the download protection feature.
Cookies set by the Safe Browsing servers to protect the service from abuse are stored in a separate cookie jar so that they are not mixed with regular browsing/session cookies.
When requesting complete hashes for a 32-bit prefix, Firefox throws in a number of extra "noise" entries to obfuscate the original URL further.
On balance, we believe that most users will want to keep Safe Browsing enabled, but we also make it easy for users with particular needs to turn it off.