Add more owners to chromeos/crosapi/mojom/OWNERS

Crosapi changes are unusual in that they are less security sensitive
than most IPC changes (since ash and lacros run at the same level of
privilege) but more sensitive to version skew issues. Given these
unique constraints we're going to let a few non-security-team owners
review small, less-security-sensitive changes. Larger changes will be
escalated to the security team. See go/lacros-mojo-security-review

Bug: none
Change-Id: I3d39cd910ba527020d9d234b8b2bc0ab8f397027
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2495509
Auto-Submit: James Cook <jamescook@chromium.org>
Commit-Queue: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820619}

chromeos/crosapi/mojom/OWNERS

 per-file *.mojom=set noparent
-per-file *.mojom=file://ipc/SECURITY_OWNERS
-# Prefer Chrome OS owners for large changes to the Lacros API.
+
+# For small changes, like adding a field to an existing API, prefer
+# Lacros owners. See go/lacros-mojo-security-review
+per-file *.mojom=file://chromeos/LACROS_OWNERS
+
+# Prefer Chrome OS owners for larger or security-sensitive changes
+# to the Lacros API. See go/lacros-mojo-security-review
 per-file *.mojom=file://chromeos/SECURITY_OWNERS
 
+# General Chrome IPC owners are a last resort.
+per-file *.mojom=file://ipc/SECURITY_OWNERS
+
 per-file *_mojom_traits*.*=set noparent
-per-file *_mojom_traits*.*=file://ipc/SECURITY_OWNERS
+per-file *.mojom_traits*.*=file://chromeos/LACROS_OWNERS
 per-file *.mojom_traits*.*=file://chromeos/SECURITY_OWNERS
+per-file *_mojom_traits*.*=file://ipc/SECURITY_OWNERS