GitLab

Based on https://codereview.chromium.org/2180683003/ and
discussions from https://codereview.chromium.org/2163453002/.

BUG=628663, 631126
TEST=views_mus_unittests, mus_public_unittests, mash_unittests,
     mus_ws_unittests

Review-Url: https://codereview.chromium.org/2183163002
Cr-Commit-Position: refs/heads/master@{#410734}