[SingleProcessMash] Disable ChromeNewWindowClientBrowserTest.NewWindowForActiveWindowProfileTest

Seeing flaky failures for the test on the MSan bot.

Bug: 884118
Change-Id: Id2773b731b054bbecb02fd9bca8f7c00d2f5f447
Reviewed-on: https://chromium-review.googlesource.com/1232193Reviewed-by: Asanka Herath <asanka@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Ryan Cui <rcui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592249}

testing/buildbot/filters/chromeos.single_process_mash.browser_tests.filter

@@ -158,6 +158,9 @@
 # Enterprise keys tests.
 -CheckSystemTokenAvailability/EnterprisePlatformKeysTest.Basic/*
 
+# Flaky test. crbug.com/884118
+-ChromeNewWindowClientBrowserTest.NewWindowForActiveWindowProfileTest
+
 # Ash native views tests.
 -ChromeNativeAppWindowViewsAuraAshBrowserTest.*