api: payload: Fill out file_path in response

We've deprecated 'local_path' in favor of a Path-typed 'file_path'
field.

BUG=b:289101910
TEST=./run_tests
TEST=`cros try release`

Change-Id: I822072c6e46d3881c28819f0eb7275e7ddae3eb4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4811831
Reviewed-by: Madeleine Hardt <hardtmad@google.com>
Tested-by: Brian Norris <briannorris@chromium.org>
Commit-Queue: Brian Norris <briannorris@chromium.org>
diff --git a/api/controller/payload.py b/api/controller/payload.py
index 0d2ebef..ded49d0 100644
--- a/api/controller/payload.py
+++ b/api/controller/payload.py
@@ -11,6 +11,7 @@
 from chromite.api import validate
 from chromite.api.controller import controller_util
 from chromite.api.gen.chromite.api import payload_pb2
+from chromite.api.gen.chromiumos import common_pb2
 from chromite.lib import cros_build_lib
 from chromite.lib.paygen import paygen_payload_lib
 from chromite.service import payload
@@ -169,5 +170,7 @@
     for version, artifact in artifacts.items():
         versioned_artifact = output_proto.versioned_artifacts.add()
         versioned_artifact.version = version
-        versioned_artifact.local_path = artifact[0] or ""
+        if artifact[0]:
+            versioned_artifact.file_path.path = artifact[0]
+            versioned_artifact.file_path.location = common_pb2.Path.INSIDE
         versioned_artifact.remote_uri = artifact[1] or ""