Disable three flaky media track tests

Bug: 1000964,1001041
Change-Id: I84d41c0f7edaddb34fb1397c7191919673a60e01
TBR: abigailbklein@google.com
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1788224
Commit-Queue: Ian Clelland <iclelland@chromium.org>
Reviewed-by: Ian Clelland <iclelland@chromium.org>
Cr-Commit-Position: refs/heads/master@{#694342}

third_party/blink/web_tests/TestExpectations

@@ -6339,5 +6339,13 @@ crbug.com/1000768 [ Linux ] external/wpt/storage/idlharness.https.any.html [ Pas
 # Partial fix to avoid a regression on eval(string) with Trusted Types enabled in Chrome 77.
 crbug.com/992424 external/wpt/trusted-types/block-eval.tentative.html [ Failure ]
 
+# Sheriff 2019-09-05
+crbug.com/1000964 media/track/track-css-user-settings-override-internal-settings.html [ Pass Failure ]
+crbug.com/1000964 virtual/audio-service/media/track/track-css-user-settings-override-internal-settings.html [ Pass Failure ]
+crbug.com/1001041 media/track/track-css-important-user-settings-override-author-settings.html [ Pass Failure ]
+crbug.com/1001041 virtual/audio-service/media/track/track-css-important-user-settings-override-author-settings.html [ Pass Failure ]
+crbug.com/1001041 media/track/track-css-author-settings-override-user-settings.html [ Pass Failure ]
+crbug.com/1001041 virtual/audio-service/media/track/track-css-author-settings-override-user-settings.html [ Pass Failure ]
+
 # Sheriff 2019-09-06
 crbug.com/998399 [ Linux ] virtual/omt-worker-fetch/external/wpt/service-workers/service-worker/worker-interception.https.html [ Pass Timeout ]