Revert "[Cast MRP] Media commands, media status, and SET_VOLUME."

This reverts commit 808c0071aaa9ec067d1dcbb69090d40156960a98.

Reason for revert:

Findit (https://goo.gl/kROfz5) identified CL at revision 622254 as the
culprit for failures in the build cycles as shown on:
https://findit-for-me.appspot.com/waterfall/culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyRAsSDVdmU3VzcGVjdGVkQ0wiMWNocm9taXVtLzgwOGMwMDcxYWFhOWVjMDY3ZDFkY2JiNjkwOTBkNDAxNTY5NjBhOTgM

Sample Failed Build: https://ci.chromium.org/buildbot/chromium.win/Win%207%20Tests%20x64%20%281%29/46830

Sample Failed Step: unit_tests

Original change's description:
> [Cast MRP] Media commands, media status, and SET_VOLUME.
> 
> Forked from https://chromium-review.googlesource.com/c/chromium/src/+/1234371
> 
> This patch implements media commands sent from the SDK to the receiver,
> as well as media status messages from the receiver to the SDK.
> 
> This patch also implements the SET_VOLUME message which sets the system
> level volume and not considered part of media commands.
> 
> Bug: 809249
> Change-Id: Ib6d0a8764ca16ec9f0c5748df16e2a7c3f972be0
> Reviewed-on: https://chromium-review.googlesource.com/c/1372666
> Commit-Queue: John Williams <jrw@chromium.org>
> Reviewed-by: mark a. foltz <mfoltz@chromium.org>
> Reviewed-by: Takumi Fujimoto <takumif@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#622254}

Change-Id: I9b92076738ec5038e93e96c1c12ac2e0cdf3ed8f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 809249
Reviewed-on: https://chromium-review.googlesource.com/c/1407266
Cr-Commit-Position: refs/heads/master@{#622292}
32 files changed