Chameleon: Check internal display in chameleon test

Add test flow in check_screen_with_chameleon() to check whether or not the
Chameleon screen matches the internal screen of DUT when DUT is under
hardware-based mirrored mode (i.e. the resolution of internal display matches
the external one.)

BUG=chromium:379878
TEST=manually run the test on peppy and see it passed.

Change-Id: Ib314856b9fc9c8c3945a7b0e77ca02d1ea2a2b7c
Reviewed-on: https://chromium-review.googlesource.com/212273
Reviewed-by: Hung-ying Tyan <tyanh@chromium.org>
Tested-by: Ting-Yuan Cheng <tingyuan@chromium.org>
Commit-Queue: Ting-Yuan Cheng <tingyuan@chromium.org>
6 files changed