Revert "Make PepperUdpSocketMessageFilter use NetworkService UDP API."

This reverts commit cc2b634dbe8b987c9946689b6d8c2388cd5466ea.

Reason for revert: Multiple PPAPI tests have begun failing on different OSes after this patch lands. See crbug.com/876824

Original change's description:
> Make PepperUdpSocketMessageFilter use NetworkService UDP API.
> 
> This CL moves all of the logic over to the UI thread, to keep things
> relatively simple and minimize thread hops, since that's where core
> network service objects live.
> 
> It also fixes a pre-existing bug in the PPAPI UDP code, where read
> errors that occur when there's no pending read are converted into
> 0-byte read successes.
> 
> Bug: 848078
> Cq-Include-Trybots: luci.chromium.try:linux_mojo
> Change-Id: Id6d23c26c1ac085211dfcfe23502a307fc29a284
> Reviewed-on: https://chromium-review.googlesource.com/1171568
> Commit-Queue: Matt Menke <mmenke@chromium.org>
> Reviewed-by: John Abd-El-Malek <jam@chromium.org>
> Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
> Reviewed-by: Helen Li <xunjieli@chromium.org>
> Reviewed-by: Bill Budge <bbudge@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#585057}

TBR=bbudge@chromium.org,jam@chromium.org,mmenke@chromium.org,xunjieli@chromium.org,rhalavati@chromium.org

Change-Id: I68b625673615275c102a95aac7df7583a2f7c97d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 848078
Cq-Include-Trybots: luci.chromium.try:linux_mojo
Reviewed-on: https://chromium-review.googlesource.com/1185682
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#585196}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 3ea4abbfded911cb15cc62f93519564983f41faf
5 files changed