Issue 4335: Disable SafeBrowsing in Tor

[jumde]

fix brave/brave-browser#4335

Description

SafeBrowsing checks in chromium send much more info than just IP and hashes. See here: https://cs.chromium.org/chromium/src/components/safe_browsing/proto/csd.proto

Disabling SafeBrowsing in tor for now.

Please use a Release version of Brave to verify this fix, issue to fix the DCHECK failures is being tracked here: brave/brave-browser#4321

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Windows
  • macOS
  • Linux
• Verified that these changes pass automated tests (npm test brave_unit_tests && npm test brave_browser_tests && npm run test-security) on
  • Windows
  • macOS
  • Linux
• Verified that all lint errors/warnings are resolved (npm run lint)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protection-Mode
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection

Test Plan:

1. Set up a clean profile
2. Wait ~2 mins to make sure the hash files for SafeBrowsing are downloaded in <DATA_DIR>/Safe\ Browsing
3. In a regular tab, navigate to https://testsafebrowsing.appspot.com - verify that safe-browsing works correctly
4. Open a tor tab, navigate to https://testsafebrowsing.appspot.com - verify that safe-browsing does not work and no connections are made to google domains.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[diracdeltas]

closing by mandate of product https://bravesoftware.slack.com/archives/C85NV6NSG/p1557176576049400?thread_ts=1557174991.034600&cid=C85NV6NSG

[diracdeltas]

defer to @riastradh-brave

[iefremov]

LGTM