GitLab

Skip native_viewport's init of gfx::GLSurface when headless.
Remove the unused --use-osmesa flag (--use-test-config suffices?).
Re-enable the window_manager_apptests again; fingers crossed.

BUG=480040
TEST=Bot passes window_manager_apptests.
R=sky@chromium.org
TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/1103413002

Cr-Commit-Position: refs/heads/master@{#327184}