Add setters to chromeos::FakeUpstartClient

This allows us to inject failures to the StartJob and StopJob
functions for better unit test coverage.

BUG=b:142144019
TEST=try

Change-Id: I17ebd3ddd74cd78bb7b123a7fda0a377d53963ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1850572Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Yusuke Sato <yusukes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704473}

chromeos/dbus/upstart/fake_upstart_client.cc

@@ -40,14 +40,14 @@ void FakeUpstartClient::StartJob(const std::string& job,
                                  const std::vector<std::string>& upstart_env,
                                  VoidDBusMethodCallback callback) {
   base::ThreadTaskRunnerHandle::Get()->PostTask(
-      FROM_HERE, base::BindOnce(std::move(callback), true));
+      FROM_HERE, base::BindOnce(std::move(callback), start_job_result_));
 }
 
 void FakeUpstartClient::StopJob(const std::string& job,
                                 const std::vector<std::string>& upstart_env,
                                 VoidDBusMethodCallback callback) {
   base::ThreadTaskRunnerHandle::Get()->PostTask(
-      FROM_HERE, base::BindOnce(std::move(callback), true));
+      FROM_HERE, base::BindOnce(std::move(callback), stop_job_result_));
 }
 
 void FakeUpstartClient::StartAuthPolicyService() {

chromeos/dbus/upstart/fake_upstart_client.h

@@ -41,7 +41,13 @@ class COMPONENT_EXPORT(UPSTART_CLIENT) FakeUpstartClient
   void StartWilcoDtcService(VoidDBusMethodCallback callback) override;
   void StopWilcoDtcService(VoidDBusMethodCallback callback) override;
 
+  void set_start_job_result(bool result) { start_job_result_ = result; }
+  void set_stop_job_result(bool result) { stop_job_result_ = result; }
+
  private:
+  bool start_job_result_ = true;
+  bool stop_job_result_ = true;
+
   DISALLOW_COPY_AND_ASSIGN(FakeUpstartClient);
 };