Issue 1985: Properly show the widevine absence prompt.

[iefremov]

Fixes brave/brave-browser#1985
Replacing a set of hardcoded urls with a blink hook and a corresponding
tab helper that updates the widevine content settings icon.

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) on
  • Windows
  • macOS
  • Linux
• 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

Test Plan:

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

[bbondy]

Could you just have 1 header file and 1 function that you insert here to minimize patching a bit here?

[bbondy]

Or even 0 header files and chromium_src override and patch 1 line to call the function from the extra header in the override.

[iefremov]

done

[bbondy]

noticed tests weren't marked above so I ran them on macOS and they all passed for me.

[bbondy]

Ran builds and tests on linux and Windows too. All pass.

[bbondy]

master (0.61.x): 1a2669f
060.x: 0b04a06

[kjozwiak]

@iefremov @bbondy uplift request to 0.59.x approved after deliberating with @srirambv & @rebron 👍 Please add/remove all required labels and ensure that the associated issue is moved to the correct milestone.

[bbondy]

0.59.x: 981f7f4