The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d30555356362aea87ee59b80174f864f8b2d0fde

commit d30555356362aea87ee59b80174f864f8b2d0fde
Author: John Rummell <jrummell@chromium.org>
Date: Fri Sep 21 20:47:25 2018

Update media UKM to include audio and video encryption scheme

Add the encryption scheme used for both the audio and video tracks to
the data saved for each media playback.

BUG= 858855 
TEST=new unittests pass

Change-Id: I477e3475f6211980d199ab7c873447d70192f719
Reviewed-on: https://chromium-review.googlesource.com/1195924
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: John Rummell <jrummell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593324}
[modify] https://crrev.com/d30555356362aea87ee59b80174f864f8b2d0fde/media/blink/watch_time_reporter_unittest.cc
[modify] https://crrev.com/d30555356362aea87ee59b80174f864f8b2d0fde/media/blink/webmediaplayer_impl.cc
[modify] https://crrev.com/d30555356362aea87ee59b80174f864f8b2d0fde/media/mojo/interfaces/watch_time_recorder.mojom
[modify] https://crrev.com/d30555356362aea87ee59b80174f864f8b2d0fde/media/mojo/services/watch_time_recorder.cc
[modify] https://crrev.com/d30555356362aea87ee59b80174f864f8b2d0fde/media/mojo/services/watch_time_recorder_unittest.cc
[modify] https://crrev.com/d30555356362aea87ee59b80174f864f8b2d0fde/tools/metrics/ukm/ukm.xml