Add chromiumos_preflight target for Chromium OS simplechrome builders
Add chromiumos_preflight target for Chromium OS simplechrome builders

This adds a type:none target that builds targets that Chrome OS compiles
in the chrome preflight build. Any breakage in these targets with this
configuration must be addressed by Chrome OS gardeners.

This allows us to avoid building "all" while still building enough targets
to avoid breaking the CrOS chrome preflight build.

BUG=489795
TEST=cros chrome-sdk --board=daisy; gclient runhooks;
  ninja -C out_daisy/Release -j1000 -k50 chromiumos_preflight

Review URL: https://codereview.chromium.org/1232893002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#338786}

ltilve/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend