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The same code is used in screen rotator and tablet mode controller.
Refactor and make it a library so that we can use it in different places
like unlock.

Bug: None

Change-Id: I6bbb99c4fc77da8a30379fa8fc4b02ad2d6c7369
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2562962
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832233}