Hook device auto-rotation to its physical tablet state

- Now auto-rotation is on, when the device is in a physical
  tablet state, regardless of the UI mode (tablet or clamshell).
- Apps' requested orientation locks are only applied while in
  UI tablet mode, and ignored in UI clamshell mode even if the
  device is in a physical tablet state.

A follow-up CL will handle changes needed for display settings.

BUG=925087
TEST=Manually, Added new tests

Change-Id: I265dd80563b4532b72ed11aa53206bdc8bfa7dba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1861049
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Mitsuru Oshima (slow) <oshima@chromium.org>
Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708484}