Reland "[DevTools] Prevent JSONReader::Read errors from invalid unicode points"

Relanding http://crrev.com/c/1399538
Reverted by http://crrev.com/c/1404161

The original test didn't wait for Network.enable to finish before making
a request and expected to see network events, which did work... when
network service wasn't turned on. With network service enabled,
Network.enable takes longer and needs to be awaited for.

browser_tests now passes with --enable-features=NetworkService

Bug: 824174, 920539, 920544
Change-Id: I3458b08ccce34ec6df6d7c0c65b5b5225ab3debc
Reviewed-on: https://chromium-review.googlesource.com/c/1405848
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Joey Arhar <jarhar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621741}
3 files changed