Re-enable MediaEngagementBrowserTest's

The tests were previously flaky because of crbug.com/884589.  Now that it's fixed, renable these tests.

The EncryptedMediaTest's used to fail for the same reason, but are now failing because of a memory leak (crbug.com/889993), so keep these disabled for now.

Bug: 884589
Change-Id: Ia394e710d47f995f64ce858a51439ad11bdc2518
Reviewed-on: https://chromium-review.googlesource.com/1249913Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Ryan Cui <rcui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595084}

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

@@ -173,7 +173,7 @@
 # Default extension tests.
 -DefaultProfileExtensionBrowserTest.NoExtensionHosts
 
-# Encrypted media tests are flaky due to race condition. crbug.com/880584
+# Encrypted media tests are failing on Asan/Lsan bot due to memory leak. crbug.com/889993
 -ECKEncryptedMediaTest.*
 -EncryptedMediaTest.*
 -CDM_9/ECKEncryptedMediaTest.*
@@ -205,12 +205,6 @@
 -ManagedWithoutPermission/ManagedWithoutPermissionPlatformKeysTest.*
 -ManagedWithPermission/ManagedWithPermissionPlatformKeysTest.*
 
-# Needs video surface layer support. Should be fixed when renderers don't use
-# the window service for embedding.
-# https://crbug.com/884589 https://crbug.com/881574
--MediaEngagementBrowserTest.*
--MediaEngagementAutoplayBrowserTest.*
-
 # Flaky https://crbug.com/887175
 -PrerenderBrowserTest.PrerenderHTML5VideoJs