buffet: Fixed command state spelling for "cancelled"

GCD spec apparently expects the command status to be spelled as
"cancelled". Fixed...

BUG=brillo:552
TEST=`FEATURES=test emerge-link buffet`

Change-Id: I11a848f2f29ca7d63ce95d130b2a84aa75ced7fd
Reviewed-on: https://chromium-review.googlesource.com/260028
Trybot-Ready: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/commands/dbus_command_proxy_unittest.cc b/buffet/commands/dbus_command_proxy_unittest.cc
index e750ddb..ff351ba 100644
--- a/buffet/commands/dbus_command_proxy_unittest.cc
+++ b/buffet/commands/dbus_command_proxy_unittest.cc
@@ -195,7 +195,7 @@
 TEST_F(DBusCommandProxyTest, Cancel) {
   EXPECT_CALL(*mock_exported_object_command_, SendSignal(_)).Times(1);
   GetCommandInterface()->Cancel();
-  EXPECT_EQ(CommandInstance::kStatusCanceled,
+  EXPECT_EQ(CommandInstance::kStatusCancelled,
             GetCommandAdaptor()->GetStatus());
 }