Remove some ash flags from chrome://flags

According to new flag ownership guideline, only flags that are actively
used by testers are allowed to be in chrome://flags, and others should
be just command line switches that are only available for developers.

As ash-enable-notification-expansion-animation is a feature that has no
clear launch timeline, and ash-enable-notification-scroll-bar is just
for debugging, let's remove them from chrome://flags.

TEST=trybot pass
BUG=None

Change-Id: Ie87b9990da2ca3d4325f624ed0a29a041170cf04
Reviewed-on: https://chromium-review.googlesource.com/c/1442073
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629008}
2 files changed