Strip referer to strict-origin-when-cross-origin in all cases

[pes10k]

This is a follow up to #13434 (which is no longer needed)

Brave currently completely strips the referrer on all cross origin top-frame navigations. This causes Brave to look like bots / fraud for some non-malicious systems (e.g., DDG and similar).

We should change Brave's referrer policy to cap at (i.e. send less when the page requests less, but cap and default to strict-origin-when-cross-origin)

[kjozwiak]

Moving into 1.21.x where it landed as this isn't labelled a release/blocking. We're not 100% sure this is going to make it into the initial 1.19.x release and might be pushed into a HF. Once that happens, it will be moved into the correct milestone.

Edited: Adding release/blocking and moving into 1.19.x after speaking with @bbondy.

[kjozwiak]

Waiting on new 1.19.x build that will include 88.0.4324.96 👍

Edited - Started 1.19.86 CR: 88.0.4324.96 which should be done in ~3-4hrs.

[GeetaSarvadnya]

Verification passed on

Brave | 1.19.86 Chromium: 88.0.4324.96 (Official Build) (64-bit)
-- | --
Revision | 68dba2d8a0b149a1d3afac56fa74648032bcf46b-refs/branch-heads/4324@{#1784}
OS | Windows 10 OS Version 2004 (Build 19041.746)

• Verified the test plan from 13464: Unrestrict referrer hiding for top-level navigations. brave-core#7591
• Verified that all the test cases on the test pages are working as expected
  https://dev-pages.brave.software/referrer/index.html
  https://fmarier.github.io/brave-testing/referrer-spoofing.html
  https://referrer.fmarier.org/redirects.html
  https://referrer.fmarier.org/samesite.html

---

Verification passed on

Brave	1.19.86 Chromium: 88.0.4324.96 (Official Build) (64-bit)
Revision	68dba2d8a0b149a1d3afac56fa74648032bcf46b-refs/branch-heads/4324@{#1784}
OS	Ubuntu 18.04 LTS

Verified the test plan from brave/brave-core#7591

---

Verified passed with

Brave | 1.19.86 Chromium: 88.0.4324.96 (Official Build) (x86_64)
-- | --
Revision | 68dba2d8a0b149a1d3afac56fa74648032bcf46b-refs/branch-heads/4324@{#1784}
OS | macOS Version 10.15.7 (Build 19H15)

Verified the test plan from brave/brave-core#7591

Confirmed tests from the following pages worked as expected:

• https://dev-pages.brave.software/referrer/index.html
• https://fmarier.github.io/brave-testing/referrer-spoofing.html
• https://referrer.fmarier.org/redirects.html
• https://referrer.fmarier.org/samesite.html

---

Verification passed on Brave v1.19.86 on Samsung Galaxy Tab S5e (Android 9.0)

Verified the test plan from brave/brave-core#7591

Confirmed tests from the following pages worked as expected:

• https://fmarier.github.io/brave-testing/referrer-spoofing.html
• https://referrer.fmarier.org/redirects.html
• https://referrer.fmarier.org/samesite.html

---

Verification PASSED on Samsung S10+ running Android 10 using the following build:

1.19.86 Chromium: 88.0.4324.96

• https://dev-pages.brave.software/referrer/index.html - PASSED
• https://fmarier.github.io/brave-testing/referrer-spoofing.html - PASSED
• https://referrer.fmarier.org/redirects.html - PASSED
• https://referrer.fmarier.org/samesite.html - PASSED