Revert of Fix race condition in content_shell which could lead to an assert on shutdown with

Revert of Fix race condition in content_shell which could lead to an assert on shutdown with PlzNavigate. (patchset #1 id:1 of https://codereview.chromium.org/2764613002/ )

Reason for revert:
Introduced ServiceWorkerNavigationPreloadTest.NetworkError crashes on Debug build.

BUG=703439
Original issue's description:
> Fix race condition in content_shell which could lead to an assert on shutdown with PlzNavigate.
> 
> The problem is that URLRequestContext's destructor checks that there are no more outstanding requests, while ResourceContext's destructor is what removes outstanding requests. In Chrome's profile implementation, the order is correct, but content_shell had a bug. This only mattered with PlzNavigate because renderer requests are deleted earlier through other codepaths.
> 
> This should fix the flakiness seen on the Marshmallow 64 bit Tester with PlzNavigate.
> 
> BUG=673806
> 
> Review-Url: https://codereview.chromium.org/2764613002
> Cr-Commit-Position: refs/heads/master@{#458216}
> Committed: https://chromium.googlesource.com/chromium/src/+/18bf53b4ccb6351759ca4a0bdc30a814aeb61137

TBR=avi@chromium.org,jam@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=673806

[horo, 2017-03-21 04:00:58]

The CQ bit was checked by horo@chromium.org

[horo, 2017-03-21 04:00:58]

Created Revert of Fix race condition in content_shell which could lead to an
assert on shutdown with PlzNavigate.

[commit-bot: I haz the power, 2017-03-21 04:03:02]

The CQ bit was unchecked by commit-bot@chromium.org

[horo, 2017-03-21 05:23:28]

The CQ bit was checked by horo@chromium.org

[horo, 2017-03-21 05:23:47]

The CQ bit was unchecked by horo@chromium.org

[commit-bot: I haz the power, 2017-03-21 05:24:17]

The CQ bit was unchecked by commit-bot@chromium.org

[horo, 2017-03-22 08:33:25]

Description was changed from

==========
Revert of Fix race condition in content_shell which could lead to an assert on
shutdown with PlzNavigate. (patchset #1 id:1 of
https://codereview.chromium.org/2764613002/ )

Reason for revert:
Introduced ServiceWorkerNavigationPreloadTest.NetworkError crashes on Debug
build.

BUG=703439


Original issue's description:
> Fix race condition in content_shell which could lead to an assert on shutdown
with PlzNavigate.
> 
> The problem is that URLRequestContext's destructor checks that there are no
more outstanding requests, while ResourceContext's destructor is what removes
outstanding requests. In Chrome's profile implementation, the order is correct,
but content_shell had a bug. This only mattered with PlzNavigate because
renderer requests are deleted earlier through other codepaths.
> 
> This should fix the flakiness seen on the Marshmallow 64 bit Tester with
PlzNavigate.
> 
> BUG=673806
> 
> Review-Url: https://codereview.chromium.org/2764613002
> Cr-Commit-Position: refs/heads/master@{#458216}
> Committed:
https://chromium.googlesource.com/chromium/src/+/18bf53b4ccb6351759ca4a0bdc30...

TBR=avi@chromium.org,jam@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=673806
==========

to

==========
Revert of Fix race condition in content_shell which could lead to an assert on
shutdown with PlzNavigate. (patchset #1 id:1 of
https://codereview.chromium.org/2764613002/ )

Reason for revert:
Introduced ServiceWorkerNavigationPreloadTest.NetworkError crashes on Debug
build.

BUG=703439


Original issue's description:
> Fix race condition in content_shell which could lead to an assert on shutdown
with PlzNavigate.
> 
> The problem is that URLRequestContext's destructor checks that there are no
more outstanding requests, while ResourceContext's destructor is what removes
outstanding requests. In Chrome's profile implementation, the order is correct,
but content_shell had a bug. This only mattered with PlzNavigate because
renderer requests are deleted earlier through other codepaths.
> 
> This should fix the flakiness seen on the Marshmallow 64 bit Tester with
PlzNavigate.
> 
> BUG=673806
> 
> Review-Url: https://codereview.chromium.org/2764613002
> Cr-Commit-Position: refs/heads/master@{#458216}
> Committed:
https://chromium.googlesource.com/chromium/src/+/18bf53b4ccb6351759ca4a0bdc30...

TBR=avi@chromium.org,jam@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=673806
==========