Deflake WebMediaPlayerMSTest.OpacityChange

This test is sensitive to the ordering of delayed vs non-delayed tasks.
We can fix this by adding a couple of  extra RunLoop().RunUntilIdle();

TBR=miu@chromium.org

Bug: 863341, 891670
Change-Id: Ia55858149464387a90450f9e9ad651139b5cb723
Reviewed-on: https://chromium-review.googlesource.com/c/1366287
Reviewed-by: Alex Clarke <alexclarke@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Commit-Queue: Alex Clarke <alexclarke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614668}
1 file changed