buffet: Provide results definition in command definition.

That allows us to provide typed results for supported commands.

BUG=chromium:435607
TEST=cros_workon_make --test buffet

Change-Id: I61b5a5b294b4d869366c821adf1ef7f6db31c7ea
Reviewed-on: https://chromium-review.googlesource.com/231322
Reviewed-by: Anton Muhin <antonm@chromium.org>
Commit-Queue: Anton Muhin <antonm@chromium.org>
Tested-by: Anton Muhin <antonm@chromium.org>
diff --git a/buffet/commands/dbus_command_dispatcher_unittest.cc b/buffet/commands/dbus_command_dispatcher_unittest.cc
index af15c1d..ed272a1 100644
--- a/buffet/commands/dbus_command_dispatcher_unittest.cc
+++ b/buffet/commands/dbus_command_dispatcher_unittest.cc
@@ -73,10 +73,12 @@
     auto json = CreateDictionaryValue(R"({
       'base': {
         'reboot': {
-          'parameters': {'delay': 'integer'}
+          'parameters': {'delay': 'integer'},
+          'results': {}
         },
         'shutdown': {
-          'parameters': {}
+          'parameters': {},
+          'results': {}
         }
       }
     })");