Make "all user" services work when packaged.

chrome/test/base/mash_browser_tests_manifest.json

 {
   "name": "exe:mash_browser_tests",
   "display_name": "Mash Browser Tests",
   "interface_provider_specs": {
     "service_manager:connector": {
       "provides": {
         "service_manager:service_factory": [
           "service_manager::mojom::ServiceFactory"
         ]
       },
       "requires": {
-        "*": [ "app" ]
+        "*": [ "app" ],
+        "service:service_manager": [
+           "service_manager:instance_per_child"
+        ]
       }
     }
   }
 }