Chameleon: Add some display_client functions used by autotest.

Adding some fuctions for querying the available resolutions, switching
resolution on chromebook and chromebox client, and rewriting some property
of the objects, is useful for display_ResolutionList autotest (CL:206962).

BUG=chromium:391681
TEST=manually run the test with CL:206962 on peppy and see it passed.

Tested-by: Yuan <tingyuan@chromium.org>
Change-Id: I95462308b3d876e9e1fd1f1ed8f799aacc0f9968
Reviewed-on: https://chromium-review.googlesource.com/206970
Reviewed-by: Hung-ying Tyan <tyanh@chromium.org>
Commit-Queue: Ting-Yuan Cheng <tingyuan@chromium.org>
Tested-by: Ting-Yuan Cheng <tingyuan@chromium.org>
2 files changed