GitLab

Wrote unit test for DemoModeDetector,  accounting for existing behavior,
and also the new behavior introduced in this CL.

R=michaelpg@chromium.org
TEST=tested manually on dev chromebook, and with demo_mode_detector_unittest.cc

Bug: 877655
Change-Id: Ibfd78ec1cf2d87c3acad71a8244e519f70601cec
Reviewed-on: https://chromium-review.googlesource.com/c/1298417
Commit-Queue: Danan S <danan@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605408}