Remove WindowMus::PrepareForServerBoundsChange, which is unused.

Bug: none
Change-Id: I2d83cfe26874ba5cdf45189da8f270272c57efce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1551682
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#648768}
3 files changed