GitLab

Instead of bitwise ORing the interstitial options, we were simply
assigning new values. This CL changes the assignment to a proper bitwise
OR so all options are maintained.

R=meacer@chromium.org,
TBR=jam@chromium.org,creis@chromium.org
BUG=415256

Review URL: https://codereview.chromium.org/578373002

Cr-Commit-Position: refs/heads/master@{#295807}