Don't block fingerprinting in extension pages

[arthuredelstein]

Resolves brave/brave-browser#26715

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:

[LaurenWags]

Verified with

Brave | 1.47.90 Chromium: 108.0.5359.48 (Official Build) nightly (x86_64)
-- | --
Revision | 18ceeca0d99318e70c00d2e04d88aa55488b5c63-refs/branch-heads/5359@{#854}
OS | macOS Version 12.6.1 (Build 21G217)

Reproduced the issue in 1.45.127

Reproduced the issue described in brave/brave-browser#26715 (comment) using 1.45.127

1. Ensured BraveScreenFingerprintingBlockerStudy:Enabled on brave://version (Release channel has this at 50%, so may need a few attempts to get this enabled)
2. Confirmed no login window shows on 1.45.x when clicking on the "Line" extension icon with the BraveScreenFingerprintingBlockerStudy is enabled.
3. Confirmed shortened display of Bitwarden popup when BraveScreenFingerprintingBlockerStudy is enabled.

brave://version	Line Extension	Bitwarden Extension

Part A of test plan - PASSED

Verified the test plan from brave/brave-browser#26715 (comment) - Part A:

Using 1.47.90, verified both extensions listed in brave/brave-browser#26715 (comment) worked as described when BraveScreenFingerprintingBlockerStudy is enabled.

brave://version	Line Extension	Bitwarden Extension

Part B of test plan - PASSED

Verified the test plan from brave/brave-browser#26715 (comment) - Part B:

Using 1.47.90, run through the cases from brave/brave-browser#23170 (comment):

Case 1: 1st launch, no Griffin - PASSED

Steps:

1. installed 1.47.90
2. launched Brave
3. opened brave://version
4. confirmed no Griffin studies listed
5. loaded https://dev-pages.brave.software/fingerprinting/farbling.html
6. clicked on Generate fingerprints
7. confirmed the This Page, Local Frame, and Remote Frame values were the same for each of the following:

• Screen resolution
• Screen resolution media query
• Available screen resolution

8. loaded https://arthuredelstein.github.io/tracking_demos/screen.html
9. moved the mouse around and examined the tracked events

Confirmed there was no farbling of the screen/window coordinates shown in the screenshot

step 3	step 7	step 9

Case 2: 2nd launch, Griffin-enabled study with Shields enabled- PASSED

(Continued from 1st launch, no Griffin test, above)
10. restarted Brave
11. opened brave://version
12. confirmed in the case you get BraveScreenFingerprintingBlockerStudy:Enabled (note, study is enabled at 100% on Nightly/Beta but only 50% on Release, so when testing on 1.45.x please be aware you may need a few attempts to get this study enabled)
13. loaded https://dev-pages.brave.software/fingerprinting/farbling.html
14. clicked on Generate fingerprints
16. loaded https://arthuredelstein.github.io/tracking_demos/screen.html
17. moved the mouse around and examined the tracked coordinates

Confirmed the values for This Page were different from Local Frame and Remote Frame (which were both the same); the only four (4) trackable events were the mouseEvent.client(X/Y) coordinates

step 11	step 13	step 16

Case 3: 2nd launch, Griffin-enabled study with Shields disabled- PASSED

1. continued from Case 2
2. disable Shields in the Shields panel
3. reload the https://dev-pages.brave.software/fingerprinting/farbling.html
4. clicked on Generate fingerprints
5. loaded https://arthuredelstein.github.io/tracking_demos/screen.html
6. disable Shields in the Shields panel
7. moved the mouse around and examined the tracked coordinates

Confirmed all values were the same; no farbling was applied

brave://version	shields down	farbling.html	screen.html

Case 4: relaunch, default/no study - PASSED

(Continued from 1st launch, no Griffin test, above)
10. restarted Brave
11. opened brave://version
12. confirmed in the case where BraveScreenFingerprintingBlockerStudy:Default (note, study is enabled at 100% on Nightly/Beta but only 50% on Release - this means I had to disable brave://flags#brave-block-screen-fingerprinting to test this on Nightly however when testing on Release 1.45.x please be aware you may need a few attempts to get this study as "Default".)
13. loaded https://dev-pages.brave.software/fingerprinting/farbling.html
14. clicked on Generate fingerprints
15. loaded https://arthuredelstein.github.io/tracking_demos/screen.html
16. moved the mouse around and examined the tracked coordinates

Confirmed there was no farbling of the screen/window coordinates shown in the screenshot

step 11	step 14	step 16