Disable flaky GuestSessionRlzTest.DeviceIsLocked

TBR=rogerta@chromium.org, rsorokin@chromium.org

Bug: 1151851
Change-Id: I1516aa2ded9edc45e26be8fc54d375cbda840a17
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2553546Reviewed-by: Alexander Hendrich <hendrich@chromium.org>
Commit-Queue: Alexander Hendrich <hendrich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#830119}

chrome/browser/chromeos/login/session/chrome_session_manager_browsertest.cc

@@ -278,7 +278,8 @@ class GuestSessionRlzTest : public InProcessBrowserTest,
   DISALLOW_COPY_AND_ASSIGN(GuestSessionRlzTest);
 };
 
-IN_PROC_BROWSER_TEST_P(GuestSessionRlzTest, DeviceIsLocked) {
+// TODO(crbug.com/1151851) flaky test
+IN_PROC_BROWSER_TEST_P(GuestSessionRlzTest, DISABLED_DeviceIsLocked) {
   base::RunLoop loop;
   UserSessionInitializer::Get()->set_init_rlz_impl_closure_for_testing(
       loop.QuitClosure());