Repair menu border on Desktop Windows and Linux
This regressed in r344651 which assumed MenuConfig::InitAura() was
always called.
Actually, (e.g.) Desktop Linux currently uses only MenuConfig data
member initializers for its values.
So to fix, change MenuConfig::use_outer_border to default to true. Set
it unconditionally to false in MenuConfig::InitAura() (which is only
called for Ash windows), and on mac.
Verified:
- Windows, Linux: border (except in --open-ash),
- chromeos, Mac: no border.
BUG=523914
TEST=Visual
Review URL: https://codereview.chromium.org/
1303313005
Cr-Commit-Position: refs/heads/master@{#345479}