Disable UserAddingScreenTest.ScreenVisibility because it's crashing

TBR=xiaohuic@chromium.org
BUG=978267

Change-Id: Iad449bb6308db01ef8bf3e38a1c6364ae0f44732
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1674749Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671909}

chrome/browser/chromeos/login/ui/user_adding_screen_browsertest.cc

@@ -258,8 +258,8 @@ IN_PROC_BROWSER_TEST_F(UserAddingScreenTest, PRE_ScreenVisibility) {
   StartupUtils::MarkOobeCompleted();
 }
 
-// Trying to catch http://crbug.com/362153.
-IN_PROC_BROWSER_TEST_F(UserAddingScreenTest, ScreenVisibility) {
+// http://crbug.com/978267
+IN_PROC_BROWSER_TEST_F(UserAddingScreenTest, DISABLED_ScreenVisibility) {
   LoginUser(test_users_[0]);
 
   UserAddingScreen::Get()->Start();