Revert of Assert sequence validity on non-thread-safe RefCount manipulations (2) (patchset #35 id:700001 of https://codereview.chromium.org/2666423002/ )

Reason for revert:
Speculative revert to see if this CL is the cause of the RenderWidgetHostViewChildFrameTest.ForwardsBeginFrameAcks failures on https://uberchromegw.corp.google.com/i/chromium.win/builders/Win%207%20Tests%20x64%20%281%29/builds/22400

Original issue's description:
> Assert sequence validity on non-thread-safe RefCount manipulations
>
> This CL adds DCHECKs to non-thread-safe base::RefCount to trace racy
> ref count manipulations. A ref counted object is considered to be bound
> to a sequence if the count is more than one. After this CL, ref count
> manipulations to a sequenced-bound one cause DCHECK failure.
>
> This CL also adds ScopedAllowCrossThreadRefCountAccess to opt out,
> and applies the opt-out as needed.
>
> BUG=688072
> CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
>
> Review-Url: https://codereview.chromium.org/2666423002
> Cr-Commit-Position: refs/heads/master@{#460773}
> Committed: https://chromium.googlesource.com/chromium/src/+/f9a212dec0fec22e21d7f66ad1aa9414ed1dc068

TBR=gab@chromium.org,raymes@chromium.org,zmo@chromium.org,yzshen@chromium.org,danakj@chromium.org,tzik@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=688072

Review-Url: https://codereview.chromium.org/2783393002
Cr-Original-Commit-Position: refs/heads/master@{#460859}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 4d5b2df34c2023956579d96e89aaaacf04e510d1
2 files changed