WebLayer: enable MediaSession WPT tests.

Bug: 1066263
Change-Id: I4d59865d6595132896afc7c5db9fbd71d2d8a18c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2268213
Commit-Queue: Evan Stade <estade@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Auto-Submit: Evan Stade <estade@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782730}

third_party/blink/web_tests/android/WeblayerWPTOverrideExpectations

@@ -2945,11 +2945,6 @@ crbug.com/1050754 external/wpt/mediacapture-streams/MediaStream-default-feature-
 crbug.com/1050754 external/wpt/mediacapture-streams/MediaStream-removetrack.https.html [ Failure ]
 crbug.com/1050754 external/wpt/mediacapture-streams/historical.https.html [ Failure ]
 crbug.com/1050754 external/wpt/mediacapture-streams/idlharness.https.window.html [ Failure ]
-crbug.com/1050754 external/wpt/mediasession/idlharness.window.html [ Failure ]
-crbug.com/1050754 external/wpt/mediasession/mediametadata.html [ Failure ]
-crbug.com/1050754 external/wpt/mediasession/playbackstate.html [ Failure ]
-crbug.com/1050754 external/wpt/mediasession/positionstate.html [ Failure ]
-crbug.com/1050754 external/wpt/mediasession/setactionhandler.html [ Failure ]
 crbug.com/1050754 external/wpt/mimesniff/mime-types/charset-parameter.window.html [ Failure ]
 crbug.com/1050754 external/wpt/mimesniff/mime-types/parsing.any.html [ Failure ]
 crbug.com/1050754 external/wpt/mimesniff/mime-types/parsing.any.worker.html [ Failure ]