Add handling of pinned tab changes to UnderlineViewUpdater

This completes the triggering logic initially added in https://crrev.com/c/6778268 with addition of the signal from pinned tab changes.

As per b:430004277, it seems that some CQ runs can fail with `[build
target] steps in test new tests for flakiness didn't produce test
results` because of lengthy test names. Skipping the flakiness check
step is the workaround

Validate-Test-Flakiness: skip
Bug: b:431791050
Change-Id: Idb2cbf5e286bf2064309e6d67073b65fbf7cf32b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6778498
Reviewed-by: Marke Hallowell <wry@chromium.org>
Reviewed-by: Michael Crouse <mcrouse@chromium.org>
Reviewed-by: Alison Gale <agale@chromium.org>
Commit-Queue: Anthony Cui <cuianthony@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1494241}