Add support for MojoChannel field trial
This adds support for the upcoming MojoChannel field trial.
It also simplifies the logic around enabling Mojo channel
in general, getting rid of compile-time overrides and instead
controlling the feature only at runtime via a single flag or
(in the absence of said flag) the field trial.
BUG=595082
R=jam@chromium.org
Review URL: https://codereview.chromium.org/1805653003
Cr-Commit-Position: refs/heads/master@{#381490}
CrOS-Libchrome-Original-Commit: b0abbd20ecfc1b84f7570ee7f5df100f043010e8
2 files changed