[Layout] Delete a bunch of unused Layout methods

These methods are unused and not overridden. They were used by legacy
tab switcher code. LayoutManagerImpl still needs stubs for some of these
events as subclasses care about the events and override the stubs.

Bug: N/A
Change-Id: I4d0ea1bf1c5516f39325a439ba7784b2c95b6145
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6663459
Auto-Submit: Calder Kitagawa <ckitagawa@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Commit-Queue: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1477402}