Comment for flaky test

R=dpapad@chromium.org

Bug: 962114
Change-Id: I4d0bc5d735d2a9286b4c522aa51fd46dbfdbd51f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1612127Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660709}

chrome/test/data/webui/settings/cr_settings_browsertest.js

@@ -2300,6 +2300,7 @@ CrSettingsCrostiniPageTest.prototype = {
   ]),
 };
 
+// TODO(crbug.com/962114): Disabled due to flakes on linux-chromeos-rel.
 TEST_F('CrSettingsCrostiniPageTest', 'DISABLED_All', function() {
   mocha.run();
 });