This makes sure we use ninja everywhere if not stated
otherwise explicitly.
BUG=chromium:474921
Review-Url: https://codereview.chromium.org/2078393002
Cr-Commit-Position: refs/heads/master@{#37095}
This prepares for pulling chromium's build as dependency for
gn. After this, the files in build and gypfiles need to stay
in sync until chromium is updated.
BUG=chromium:474921
LOG=n
Review-Url: https://codereview.chromium.org/1848553003
Cr-Commit-Position: refs/heads/master@{#35898}