Update setdep to take in optional output_file

Bug: b/328065301
Change-Id: I3b17fecd8542ac19a3dfcff1cc830bb7e194d953
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5518038
Reviewed-by: Joanna Wang <jojwang@chromium.org>
Commit-Queue: Stephanie Kim <kimstephanie@google.com>

gclient.py

@@ -4183,16 +4183,19 @@ def CMDsetdep(parser, args):
             raw_objects = value.split('?')
             for o in raw_objects:
                 object_info = o.split(',')
-                if len(object_info) != 4:
+                if len(object_info) != 4 and len(object_info) != 5:
                     parser.error(
-                        'All 4 values are required in the revision object: '
-                        'object_name, sha256sum, size_bytes, and generation.')
+                        'All values are required in the revision object: '
+                        'object_name, sha256sum, size_bytes, generation, '
+                        'and (optional) output_file.')
                 object_dict = {
                     'object_name': object_info[0],
                     'sha256sum': object_info[1],
                     'size_bytes': object_info[2],
                     'generation': object_info[3],
                 }
+                if len(object_info) == 5:
+                    object_dict['output_file'] = object_info[4]
                 objects.append(object_dict)
             gclient_eval.SetGCS(local_scope, name, objects)
         else: