Mark test as flaky.

BUG=871784
TBR=joenotcharles@chromium.org

Change-Id: I0c54a4f46a9fdf5fb8aa358b6cd4ed06d9be797b
Reviewed-on: https://chromium-review.googlesource.com/1165309Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Joe Mason <joenotcharles@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581235}

chrome/chrome_cleaner/os/system_util_cleaner_unittest.cc

@@ -84,7 +84,8 @@ TEST_F(ServiceUtilCleanerTest, DeleteService) {
   EXPECT_FALSE(DoesServiceExist(service_handle.service_name()));
 }
 
-TEST_F(ServiceUtilCleanerTest, StopAndDeleteRunningService) {
+// Flaky. https://crbug.com/871784
+TEST_F(ServiceUtilCleanerTest, FLAKY_StopAndDeleteRunningService) {
   // Install and launch the service.
   TestScopedServiceHandle service_handle;
   ASSERT_TRUE(service_handle.InstallService());
@@ -107,7 +108,8 @@ TEST_F(ServiceUtilCleanerTest, StopAndDeleteRunningService) {
   EXPECT_FALSE(IsProcessRunning(kTestServiceExecutableName));
 }
 
-TEST_F(ServiceUtilCleanerTest, DeleteRunningService) {
+// Flaky. https://crbug.com/871784
+TEST_F(ServiceUtilCleanerTest, FLAKY_DeleteRunningService) {
   // Install and launch the service.
   TestScopedServiceHandle service_handle;
   ASSERT_TRUE(service_handle.InstallService());