Allow UI startup to proceed even if test list is broken.

Display the error in a dialog in the UI.

BUG=None
TEST=Manual

Change-Id: Ib93e5403f04ee18f2aade0a93656c9b4808906c9
Reviewed-on: https://gerrit.chromium.org/gerrit/42852
Tested-by: Jon Salz <jsalz@chromium.org>
Reviewed-by: Cheng-Yi Chiang <cychiang@chromium.org>
Commit-Queue: Jon Salz <jsalz@chromium.org>
3 files changed