GitLab

Update the native_viewport CommandLine usage pattern.
(codereview.chromium.org/1057603003 removed per-app args)

Re-enable window_manager_apptests with test and headless flags.
(our FYI waterfall: http://build.chromium.org/p/chromium.mojo/console)

BUG=480040
TEST=Tests pass on the waterfall.
R=sky@chromium.org
TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/1107133002

Cr-Commit-Position: refs/heads/master@{#327139}