MidiHost: Do not trust Mojo calls

Current implementation doesn't follow the recent best practice,
and may be confused on unexpected request sequences from
untrustworthy processes.

So, this patch changes not to rely on DCHECK,and not to just pass
the request to the internal service, but to have a validation for
incoming calls, and raise a bad message report.

Change-Id: I67973489007b69f56107963cef16333c4a6f5d28
Bug: 403402800
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6395593
Reviewed-by: Michael Wilson <mjwilson@chromium.org>
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Paul Semel <paulsemel@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1438582}