I think we should revert on failures; the test is on FYI but needs to be moved to main waterfall as network service is supported now.

Sure, I'll revert that CL.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a7fe6dfa93848704dd2eff05fe40656c6254328d

commit a7fe6dfa93848704dd2eff05fe40656c6254328d
Author: Jun Cai <juncai@chromium.org>
Date: Wed Dec 05 20:38:50 2018

Revert "DCHECK: Successful URL load requires a response's body"

This reverts commit 0bc656bf1d60b779bda6503f8852a8e0964725d5.

Reason for revert: During network service sheriffing, noticed that the Mojo Linux bot started failing from:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mojo%20Linux/23165
and two layout tests failed:
http/tests/worklet/import-filesystem-url.html
virtual/threaded/http/tests/worklet/import-filesystem-url.html

It looks like it is related to this CL.

Original change's description:
> DCHECK: Successful URL load requires a response's body
> 
> DCHECK that when URLLoaderClient::OnComplete(net::OK) is called, a
> response's body has been received before.
> 
> Bug: 831155, 826868 
> Change-Id: I821267f5fdefcc1e8f18be6a96138237207e7b77
> Reviewed-on: https://chromium-review.googlesource.com/c/1352259
> Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#613936}

TBR=kinuko@chromium.org,arthursonzogni@chromium.org, jam@chromium.org

Change-Id: I61cb591566839e6587390de82e90d8ccf08edfdd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 831155,  826868 ,  912293 
Reviewed-on: https://chromium-review.googlesource.com/c/1363899
Reviewed-by: Jun Cai <juncai@chromium.org>
Commit-Queue: Jun Cai <juncai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614085}
[modify] https://crrev.com/a7fe6dfa93848704dd2eff05fe40656c6254328d/content/renderer/loader/url_loader_client_impl.cc
[modify] https://crrev.com/a7fe6dfa93848704dd2eff05fe40656c6254328d/content/renderer/loader/url_loader_client_impl.h
[modify] https://crrev.com/a7fe6dfa93848704dd2eff05fe40656c6254328d/content/renderer/loader/url_loader_client_impl_unittest.cc

I need to find the remaining URLLoader(s), fix it/them and reland this DCHECK.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/93f4cecd7900f827c4eab321b64072650a92ef6d

commit 93f4cecd7900f827c4eab321b64072650a92ef6d
Author: Arthur Sonzogni <arthursonzogni@chromium.org>
Date: Fri Dec 07 08:27:16 2018

FileSystemURLLoader: always send response's body.

When a file is empty, the FileSystemURLLoader must send the response's
head, but also the response's body. The latter was missing.

Bug: 831155, 826868 , 912293 
Change-Id: I51805ca596bd7d97e04221f24222e15576a20d34
Reviewed-on: https://chromium-review.googlesource.com/c/1365431
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614641}
[modify] https://crrev.com/93f4cecd7900f827c4eab321b64072650a92ef6d/content/browser/fileapi/file_system_url_loader_factory.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a727d4b76ffcdf8c3dc03e19a08c90d217420c62

commit a727d4b76ffcdf8c3dc03e19a08c90d217420c62
Author: Arthur Sonzogni <arthursonzogni@chromium.org>
Date: Mon Dec 10 09:10:18 2018

(reland) DCHECK: Successful URL load requires a response's body

Reland of https://chromium-review.googlesource.com/c/chromium/src/+/1352259

DCHECK that when URLLoaderClient::OnComplete(net::OK) is called, a
response's body has been received before.

Bug: 831155, 826868 , 912293 
Change-Id: I387fc3930cf3ffadbd6a8ddb6b96c30c4dbc1120
Reviewed-on: https://chromium-review.googlesource.com/c/1352259
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#613936}
Reviewed-on: https://chromium-review.googlesource.com/c/1365234
Cr-Commit-Position: refs/heads/master@{#615069}
[modify] https://crrev.com/a727d4b76ffcdf8c3dc03e19a08c90d217420c62/content/renderer/loader/url_loader_client_impl.cc
[modify] https://crrev.com/a727d4b76ffcdf8c3dc03e19a08c90d217420c62/content/renderer/loader/url_loader_client_impl.h
[modify] https://crrev.com/a727d4b76ffcdf8c3dc03e19a08c90d217420c62/content/renderer/loader/url_loader_client_impl_unittest.cc