dbus: Use |upstart_env| in UpstartClient::StopJob()

Currently the argument is unused but it should be used.

BUG=none
TEST=Stop an Upstart job with nonempty environment.

Change-Id: I5b6485a79a357cb900b3672248d695a376249084
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2526662Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Youkichi Hosoi <youkichihosoi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825910}

chromeos/dbus/upstart/upstart_client.cc

@@ -56,7 +56,7 @@ class UpstartClientImpl : public UpstartClient {
   void StopJob(const std::string& job,
                const std::vector<std::string>& upstart_env,
                VoidDBusMethodCallback callback) override {
-    CallJobMethod(job, kStopMethod, {}, std::move(callback));
+    CallJobMethod(job, kStopMethod, upstart_env, std::move(callback));
   }
 
   void StartAuthPolicyService() override {