Disable flaky test on CrOS.

Bug: 946024
Change-Id: I62b07d3899814007a6ba3331c4888b9475f29033
TBR: noel
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539133Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644639}

chrome/browser/chromeos/policy/user_affiliation_browsertest.cc

@@ -309,7 +309,8 @@ IN_PROC_BROWSER_TEST_P(UserAffiliationBrowserTest, TestAffiliation) {
   ASSERT_NO_FATAL_FAILURE(VerifyAffiliationExpectations());
 }
 
-INSTANTIATE_TEST_SUITE_P(AffiliationCheck,
+// TODO(https://crbug.com/946024): PRE_ test is flakily timing out.
+INSTANTIATE_TEST_SUITE_P(DISABLED_AffiliationCheck,
                          UserAffiliationBrowserTest,
                          //         affiliated            active_directory
                          //              |                         |