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
Commit-Queue: Matt Menke <>
Reviewed-by: John Abd-El-Malek <>
Reviewed-by: Ramin Halavati <>
Reviewed-by: Helen Li <>
Reviewed-by: Bill Budge <>
Cr-Original-Commit-Position: refs/heads/master@{#585057}
Cr-Mirrored-Commit: cc2b634dbe8b987c9946689b6d8c2388cd5466ea
5 files changed