GitLab

Remove existing single OS enabled_features from BUILD files.

Update existing flags to match GN-style names where needed.

Change-Id: I052c1b25d2ee79194fe82132df59fd95cce88598
Reviewed-on: https://chromium-review.googlesource.com/920561Reviewed-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Eve Martin-Jones <evem@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537191}