Revert "[PDF Ink Signatures] Use textbox state in pdf-viewer"

This reverts commit 285f51d2a198ecb60ff824388e022ac2740307a6.

Reason for revert: Suspicious about causing the following test failure flakiness.
All/PDFExtensionJSInk2Test.Ink2ViewerToolbar/0
All/PDFExtensionJSInk2Test.Ink2ViewerToolbar/1
Bots:
https://ci.chromium.org/ui/p/chromium/builders/ci/Mac13%20Tests
https://ci.chromium.org/ui/p/chromium/builders/ci/Mac12%20Tests
https://ci.chromium.org/ui/p/chromium/builders/ci/Mac11%20Tests
Example failures:
https://ci.chromium.org/ui/b/8715572757105654433
https://ci.chromium.org/ui/b/8715568827631654529
https://ci.chromium.org/ui/b/8715575630556840977
https://ci.chromium.org/ui/b/8715577145705878225
https://ci.chromium.org/ui/b/8715570666589349409

Bug: 412640663, 412640664
Original change's description:
> [PDF Ink Signatures] Use textbox state in pdf-viewer
>
> The state is used to:
> (1) Disable undo/redo buttons while the user is adding or editing an
>     annotation.
> (2) Show the before unload dialog if the user tries to close with an
>     edited annotation open.
> (3) Set the value for whether there are edits to save based on whether
>     there is an edited annotation text box open.
> (4) Determine if the box should be committed by calling
>     commitTextAnnotation() (now made public), if the user attempts to
>     save while the box is open.
>
> Also fire an event from the Ink2Manager when an edited annotation is
> committed, in order to correctly increment the stroke count for undo
> and redo.
>
> Bug: 412640663, 412640664
> Change-Id: Ib2c34833fd250cbfe1a6fa8b3d751eebbe503610
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6484638
> Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
> Reviewed-by: Andy Phan <andyphan@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1456622}

Bug: 412640663, 412640664
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I0be62115b419cfa66502a9514ea7dceb80227a14
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6517933
Owners-Override: Yuki Shiino <yukishiino@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1456715}