api: Plumb Chroot.out_path into router/controller

We're not yet using this for anything, but let's get the API mechanics
in place.

BUG=b:265885353
TEST=./run_tests

Change-Id: Ieec3f8c4f74af99b3a043997c3fb9bad703fb7e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4327886
Commit-Queue: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
diff --git a/api/router.py b/api/router.py
index e6bae4d..e3aa62d 100644
--- a/api/router.py
+++ b/api/router.py
@@ -385,7 +385,9 @@
             )
 
             # Parse goma.
-            chroot.goma = field_handler.handle_goma(input_msg, chroot.path)
+            chroot.goma = field_handler.handle_goma(
+                input_msg, chroot.path, chroot.out_path
+            )
 
             # Parse remoteexec.
             chroot.remoteexec = field_handler.handle_remoteexec(input_msg)