Fixes client hints UA to have invariable brand name.

[mkarolin]

Fixes brave/brave-browser#25459

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

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, 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-Protections
  • 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-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[mkarolin]

Added a unit test.

[kjozwiak]

Nightly channel (Desktop verification)

AllowCertainClientHintsStudy:Enabled (set as 50%)

Windows

Verification PASSED on Win 11 x64 using the following build(s):

Brave | 1.46.32 Chromium: 106.0.5249.91 (Official Build) nightly (64-bit)
-- | --
Revision | fa96d5f07b1177d1bf5009f647a5b8c629762157-refs/branch-heads/5249@{#707}
OS | Windows 11 Version 22H2 (Build 22621.521)

Launched 1.46.32 Chromium: 106.0.5249.91 using brave.exe --enable-logging=stderr --variations-server-url=https://variations.bravesoftware.com/seed and ensured the following:

sec-ch-ua: "Chromium";v="106", "Brave";v="106", "Not;A=Brand";v="99"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"

Example	Example

Linux

Verification PASSED on PopOS 22.04 x64 using the following build(s):

Brave | 1.46.32 Chromium: 106.0.5249.91 (Official Build) nightly (64-bit) 
--- | ---
Revision | fa96d5f07b1177d1bf5009f647a5b8c629762157-refs/branch-heads/5249@{#707}
OS | Linux

Launched 1.46.32 Chromium: 106.0.5249.91 using brave.exe --enable-logging=stderr --variations-server-url=https://variations.bravesoftware.com/seed and ensured the following:

sec-ch-ua: "Chromium";v="106", "Brave";v="106", "Not;A=Brand";v="99"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Linux"

Example	Example

macOS

Verification PASSED on macOS 12.6 Monterey x64 using the following build(s):

Brave | 1.46.32 Chromium: 106.0.5249.91 (Official Build) nightly (x86_64)
--- | ---
Revision | fa96d5f07b1177d1bf5009f647a5b8c629762157-refs/branch-heads/5249@{#707}
OS | macOS Version 12.6 (Build 21G115)

Launched 1.45.41 Chromium: 105.0.5195.102 using brave.exe --enable-logging=stderr --variations-server-url=https://variations.bravesoftware.com/seed and ensured the following:

sec-ch-ua: "Chromium";v="106", "Brave";v="106", "Not;A=Brand";v="99"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "macOS"

Example	Example

AllowCertainClientHintsStudy:Disabled (set as 50%)

Windows

Verification PASSED on Win 11 x64 using the following build(s):

Brave | 1.46.32 Chromium: 106.0.5249.91 (Official Build) nightly (64-bit)
-- | --
Revision | fa96d5f07b1177d1bf5009f647a5b8c629762157-refs/branch-heads/5249@{#707}
OS | Windows 11 Version 22H2 (Build 22621.521)

Launched 1.46.32 Chromium: 106.0.5249.91 using brave.exe --enable-logging=stderr --variations-server-url=https://variations.bravesoftware.com/seed and ensured the following:

• ensured that sec-ch-ua, sec-ch-ua-mobile & sec-ch-platform weren't present via the Request Headers

Example	Example

Linux

Verification PASSED on PopOS 22.04 x64 using the following build(s):

Brave | 1.46.32 Chromium: 106.0.5249.91 (Official Build) nightly (64-bit)
--- | ---
Revision | fa96d5f07b1177d1bf5009f647a5b8c629762157-refs/branch-heads/5249@{#707}
OS | Linux

Launched 1.46.32 Chromium: 106.0.5249.91 using brave.exe --enable-logging=stderr --variations-server-url=https://variations.bravesoftware.com/seed and ensured the following:

• ensured that sec-ch-ua, sec-ch-ua-mobile & sec-ch-platform weren't present via the Request Headers

Example	Example

macOS

Verification PASSED on macOS 12.5.1 Monterey x64 using the following build(s):

Brave | 1.46.32 Chromium: 106.0.5249.91 (Official Build) nightly (x86_64) 
--- | ---
Revision | fa96d5f07b1177d1bf5009f647a5b8c629762157-refs/branch-heads/5249@{#707}
OS | macOS Version 12.6 (Build 21G115)

Launched 1.46.32 Chromium: 106.0.5249.91 using brave.exe --enable-logging=stderr --variations-server-url=https://variations.bravesoftware.com/seed and ensured the following:

• ensured that sec-ch-ua, sec-ch-ua-mobile & sec-ch-platform weren't present via the Request Headers

Example	Example

[kjozwiak]

Nightly channel (Android/Mobile verification)

AllowCertainClientHintsStudy:Enabled (set as 50%)

Verification PASSED on Samsung S10+ running Android 12 using the following build(s):

Brave | 1.46.32 Chromium: 106.0.5249.91 (Official Build) canary (32-bit)
--- | ---
Revision | fa96d5f07b1177d1bf5009f647a5b8c629762157-refs/branch-heads/5249@{#707}
OS | Android 12; Build/SP1A.210812.016

Launched 1.46.32 Chromium: 106.0.5249.91 using the instructions outlined via #10408 (comment) and ensured the following:

sec-ch-ua: "Chromium";v="106", "Brave";v="106", "Not;A=Brand";v="99"
sec-ch-ua-mobile: ?1
sec-ch-ua-platform: "Android"

Example	Example

AllowCertainClientHintsStudy:Disabled (set as 50%)

Verification PASSED on Samsung S10+ running Android 12 using the following build(s):

Brave | 1.46.32 Chromium: 106.0.5249.91 (Official Build) canary (32-bit)
--- | ---
Revision | fa96d5f07b1177d1bf5009f647a5b8c629762157-refs/branch-heads/5249@{#707}
OS | Android 12; Build/SP1A.210812.016

Launched 1.46.32 Chromium: 106.0.5249.91 using the instructions outlined via #10408 (comment) and ensured the following:

• ensured that sec-ch-ua, sec-ch-ua-mobile & sec-ch-platform weren't present via the Request Headers

Example	Example