As of now, chrome --mash is possible to get launched on regular
chrome desktop Linux builds (with enable_package_mash_services = true)
and on chromeos builds.

CL provides a first step for running with chrome --mash
natively on both Wayland and X11, through Ozone.
It includes 3 stub'ed methods for now, to be implemented follow up CLs.

GN args:
  use_ozone = true
  ozone_platform_wayland = true
  ozone_platform_x11 = true
  ozone_auto_platforms = false
  enable_package_mash_services = true

Additionally, CL also makes it possible to turn green the FYI
linux/ozone bot, worked out by thomasanderson@ et al.

TEST= <out>/chrome --mash --ozone-platform=wayland|x11 --user-data-dir=~/tmp

BUG=295089

Review-Url: https://codereview.chromium.org/2408803002
Cr-Commit-Position: refs/heads/master@{#430424}