reliably activate titleMode based on mouse state

[cezaraugusto]

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).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.

Auditors: @bbondy, @bsclifton
fix #9410

Test Plan:

General manual test plan is to:

Check when mouse is over navigation content, titleMode should be active. Otherwise it should not.

Also shortcuts such as cmd/ctrl+L and f6 should activate urlbar even when mouse is not over navigation content.

Below specific steps for bugs found in different platforms.

on macOS

1. Have the window not maximized
2. Move mouse over navigation content.
3. urlbar is active, that's ok
4. Move mouse out of window
5. titleMode should be active (urlbar should be hidden)

on Windows

1. Have the window not maximized
2. Move mouse over navigation content.
3. urlbar is active, that's ok
4. Move mouse out of window
5. titleMode is active, that's ok
6. Move mouse from top of the window up to website's title
7. titleMode should be removed (urlbar should be active)

alert active

1. Open jsFiddle.net and type under js console alert()
2. Alert is open
3. titleMode should be active (no visible urlbar)

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[cezaraugusto]

I tested both with and without this forced display and as far as I can tell no visual changes between them. In both cases, setting page to auto-refresh removes titleMode temporarily and letting tab idle while navigating other tab didn't make any action. Please let me know if I should test another scenario for tabnapping.

[cezaraugusto]

btw I also confirmed with @bradleyrichter that titleMode should be always on when mouse is over navigation chrome and aways off when it is not. Currently, it is off when you move your mouse out of the window going all way top. This is not expected and was removed in this PR.

[bradleyrichter]

@cezaraugusto I think you mean the inverse. When the mouse is in the title/search bar area, titlemode should be OFF and URL search bar mode should be ON. When the mouse exits the URL bar area, titlemode should return to on.

[bsclifton]

before I forget: we'll want to test this logic when an alert is open (because an alert forces title mode)

[cezaraugusto]

@bsclifton ok I updated STR with that, seems working as expected

[luixxiul]

test plan works. LGTM.

[bsclifton]

Changes work great 😄

There is something I noticed which will need a follow up- I'll create an issue and share here