GitLab

Ensure that queued read tasks don't make use of a null
MojoDataPipeReader.  Also ensure that error_callback_ is invoked at
most once per RemotingSender.

Bug: 1081111
Change-Id: I75d808bf2c7e747d6306543aedcac5ce26acfa97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2446992
Commit-Queue: mark a. foltz <mfoltz@chromium.org>
Reviewed-by: Yuri Wiitala <miu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816667}