Revert of Avoid cross thread malloc / free pair of IOBuffer on the simple cache

Revert of Avoid cross thread malloc / free pair of IOBuffer on the simple cache (patchset #2 id:20001 of https://codereview.chromium.org/2815563002/ )

Reason for revert:
Another large memory reduction seems to land in the same batch of the performance dashboard job, and it hid the improvement of this CL.
Revert this for now and will reland later.

Original issue's description:
> Avoid cross thread malloc/free pair of IOBuffer on the simple cache
> 
> This CL removes a cross thread malloc/free pair from simple disk cache backend.
> 
> After a PostTaskAndReply change in http://crrev.com/e5de8d551e80115b, it
> destroys |task| part of the given tasks on the target thread, and that
> introduced a number of cross thread malloc/free pairs around net::IOBuffer.
> The cross thread malloc/free pair increased the apparent size of memory
> usage on some Android perf bots by 2~3%, that is likely due to thread
> specific free list caches.
> 
> BUG=708644
> 
> Review-Url: https://codereview.chromium.org/2815563002
> Cr-Commit-Position: refs/heads/master@{#464338}
> Committed: https://chromium.googlesource.com/chromium/src/+/1714b61635cc8207647b1a9857e8042fbb833025

TBR=pmeenan@chromium.org,primiano@chromium.org,jkarlin@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=708644
Review-Url: https://codereview.chromium.org/2814743011
Cr-Commit-Position: refs/heads/master@{#464551}
Committed: https://chromium.googlesource.com/chromium/src/+/9fcfc8861ae30d5f1f5acf2d4cc0237f7f4e4f59

[tzik, 2017-04-13 21:29:29]

The CQ bit was checked by tzik@chromium.org

[tzik, 2017-04-13 21:29:29]

Created Revert of Avoid cross thread malloc / free pair of IOBuffer on the
simple cache

[commit-bot: I haz the power, 2017-04-13 21:30:26]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-13 21:31:14]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1492118969516800, "parent_rev":
"01290e8c82c71cec17fc4c15773aa21d0ee26306", "commit_rev":
"9fcfc8861ae30d5f1f5acf2d4cc0237f7f4e4f59"}

[commit-bot: I haz the power, 2017-04-13 21:32:09]

Description was changed from

==========
Revert of Avoid cross thread malloc / free pair of IOBuffer on the simple cache
(patchset #2 id:20001 of https://codereview.chromium.org/2815563002/ )

Reason for revert:
Another large memory reduction seems to land in the same batch of the
performance dashboard job, and it hid the improvement of this CL.
Revert this for now and will reland later.

Original issue's description:
> Avoid cross thread malloc/free pair of IOBuffer on the simple cache
> 
> This CL removes a cross thread malloc/free pair from simple disk cache
backend.
> 
> After a PostTaskAndReply change in http://crrev.com/e5de8d551e80115b, it
> destroys |task| part of the given tasks on the target thread, and that
> introduced a number of cross thread malloc/free pairs around net::IOBuffer.
> The cross thread malloc/free pair increased the apparent size of memory
> usage on some Android perf bots by 2~3%, that is likely due to thread
> specific free list caches.
> 
> BUG=708644
> 
> Review-Url: https://codereview.chromium.org/2815563002
> Cr-Commit-Position: refs/heads/master@{#464338}
> Committed:
https://chromium.googlesource.com/chromium/src/+/1714b61635cc8207647b1a9857e8...

TBR=pmeenan@chromium.org,primiano@chromium.org,jkarlin@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=708644
==========

to

==========
Revert of Avoid cross thread malloc / free pair of IOBuffer on the simple cache
(patchset #2 id:20001 of https://codereview.chromium.org/2815563002/ )

Reason for revert:
Another large memory reduction seems to land in the same batch of the
performance dashboard job, and it hid the improvement of this CL.
Revert this for now and will reland later.

Original issue's description:
> Avoid cross thread malloc/free pair of IOBuffer on the simple cache
> 
> This CL removes a cross thread malloc/free pair from simple disk cache
backend.
> 
> After a PostTaskAndReply change in http://crrev.com/e5de8d551e80115b, it
> destroys |task| part of the given tasks on the target thread, and that
> introduced a number of cross thread malloc/free pairs around net::IOBuffer.
> The cross thread malloc/free pair increased the apparent size of memory
> usage on some Android perf bots by 2~3%, that is likely due to thread
> specific free list caches.
> 
> BUG=708644
> 
> Review-Url: https://codereview.chromium.org/2815563002
> Cr-Commit-Position: refs/heads/master@{#464338}
> Committed:
https://chromium.googlesource.com/chromium/src/+/1714b61635cc8207647b1a9857e8...

TBR=pmeenan@chromium.org,primiano@chromium.org,jkarlin@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=708644

Review-Url: https://codereview.chromium.org/2814743011
Cr-Commit-Position: refs/heads/master@{#464551}
Committed:
https://chromium.googlesource.com/chromium/src/+/9fcfc8861ae30d5f1f5acf2d4cc0...
==========

[commit-bot: I haz the power, 2017-04-13 21:32:11]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/9fcfc8861ae30d5f1f5acf2d4cc0...