Handle milestone_version and full_version in packages.GetTargetVersions.

BUG=chromium:1004438
TEST=manual, run_tests

Change-Id: Ic385fa5f45afe91b30e7b9be304c0e503771da87
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1872174
Tested-by: Michael Mortensen <mmortensen@google.com>
Commit-Queue: Michael Mortensen <mmortensen@google.com>
Reviewed-by: Alex Klein <saklein@chromium.org>
diff --git a/api/controller/packages.py b/api/controller/packages.py
index f5c84fa..772d17e 100644
--- a/api/controller/packages.py
+++ b/api/controller/packages.py
@@ -133,7 +133,8 @@
     output_proto.chrome_version = packages.determine_chrome_version(
         build_target)
   output_proto.platform_version = packages.determine_platform_version()
-  # TODO(crbug.com/1004438): Implement remaining version fields.
+  output_proto.milestone_version = packages.determine_milestone_version()
+  output_proto.full_version = packages.determine_full_version()
 
 
 @faux.success(_HasChromePrebuiltSuccess)