Allow Safe Browsing Proxied Real Time Checks

This controls whether Safe Browsing's standard protection mode is allowed to
send partial hashes of URLs to Google through a proxy via Oblivious HTTP
in order to determine whether they are safe to visit.

The proxy allows browsers to upload partial hashes of URLs to Google
without them being linked to the user's IP address. The policy also allows
browsers to upload the partial hashes of URLs with higher frequency for
better Safe Browsing protection quality.

This policy will be ignored if Safe Browsing is disabled or set to enhanced
protection mode.

Setting the policy to Enabled or leaving it unset allows the
higher-protection proxied lookups.

Setting the policy to Disabled disallows the higher-protection proxied
lookups. Partial hashes of URLs will be uploaded to Google directly with much
lower frequency, which will degrade protection.