Convert MjpegDecodeAccelerator to new Mojo types

This CL converts MjpegDecodeAccelerator to new Mojo types
using PendingReceiver, PendingRemote, and Remote.

Bug: 955171
Change-Id: If5df104401e04075180f447ac1474a80b147ecbe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1849733
Reviewed-by: Ken Rockot <rockot@google.com>
Reviewed-by: Jonathan Backer <backer@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Ricky Liang <jcliang@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Julie Kim <jkim@igalia.com>
Cr-Commit-Position: refs/heads/master@{#705423}
22 files changed