Revert of Document that HistoryBackend is sequence-affine, not thread-affine.

Revert of Document that HistoryBackend is sequence-affine, not thread-affine. (patchset #2 id:20001 of https://codereview.chromium.org/2591123004/ )

Reason for revert:
https://uberchromegw.corp.google.com/i/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/20846/steps/browser_tests/logs/ProfileBrowserTest.OffTheRecordURLRequestContextIsolation

The CL causes the browser_tests failure on Linux ChromiumOS Tests(dbg)

Original issue's description:
> Document that HistoryBackend is sequence-affine, not thread-affine.
>
> HistoryBackend methods must not be called concurrently and external
> synchronization is required between calls on different thread.
> However, the methods do not have to be called from a single thread.
> This CL documents this and adds DCHECKs to verify that
> HistoryBackend methods are called in sequence.
>
> BUG=675800, 675631
>
> Committed: https://crrev.com/0b0b5aab6e2474e0e758ca3777b07321e59a7463
> Cr-Commit-Position: refs/heads/master@{#440408}

TBR=sdefresne@chromium.org,fdoray@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=675800, 675631
Committed: https://crrev.com/cc870ed0d9a16f478dd5e2f584ed19b749f2729f
Cr-Commit-Position: refs/heads/master@{#440441}

[Peng, 2016-12-22 16:54:11]

The CQ bit was checked by penghuang@chromium.org

[Peng, 2016-12-22 16:54:11]

Created Revert of Document that HistoryBackend is sequence-affine, not
thread-affine.

[commit-bot: I haz the power, 2016-12-22 16:54:30]

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, 2016-12-22 16:55:08]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1482425651185140, "parent_rev":
"b4f2ef26f039fae978a012f0cfd4f0033a1e1eea", "commit_rev":
"19d5b4921efee0f7a2ac356c3893b38c3520fd36"}

[commit-bot: I haz the power, 2016-12-22 16:55:33]

Description was changed from

==========
Revert of Document that HistoryBackend is sequence-affine, not thread-affine.
(patchset #2 id:20001 of https://codereview.chromium.org/2591123004/ )

Reason for revert:
https://uberchromegw.corp.google.com/i/chromium.chromiumos/builders/Linux%20C...

The CL causes the browser_tests failure on Linux ChromiumOS Tests(dbg) 

Original issue's description:
> Document that HistoryBackend is sequence-affine, not thread-affine.
> 
> HistoryBackend methods must not be called concurrently and external
> synchronization is required between calls on different thread.
> However, the methods do not have to be called from a single thread.
> This CL documents this and adds DCHECKs to verify that
> HistoryBackend methods are called in sequence.
> 
> BUG=675800, 675631
> 
> Committed: https://crrev.com/0b0b5aab6e2474e0e758ca3777b07321e59a7463
> Cr-Commit-Position: refs/heads/master@{#440408}

TBR=sdefresne@chromium.org,fdoray@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=675800, 675631
==========

to

==========
Revert of Document that HistoryBackend is sequence-affine, not thread-affine.
(patchset #2 id:20001 of https://codereview.chromium.org/2591123004/ )

Reason for revert:
https://uberchromegw.corp.google.com/i/chromium.chromiumos/builders/Linux%20C...

The CL causes the browser_tests failure on Linux ChromiumOS Tests(dbg) 

Original issue's description:
> Document that HistoryBackend is sequence-affine, not thread-affine.
> 
> HistoryBackend methods must not be called concurrently and external
> synchronization is required between calls on different thread.
> However, the methods do not have to be called from a single thread.
> This CL documents this and adds DCHECKs to verify that
> HistoryBackend methods are called in sequence.
> 
> BUG=675800, 675631
> 
> Committed: https://crrev.com/0b0b5aab6e2474e0e758ca3777b07321e59a7463
> Cr-Commit-Position: refs/heads/master@{#440408}

TBR=sdefresne@chromium.org,fdoray@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=675800, 675631

Review-Url: https://codereview.chromium.org/2599803002
==========

[commit-bot: I haz the power, 2016-12-22 16:55:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-12-22 16:59:32]

Description was changed from

==========
Revert of Document that HistoryBackend is sequence-affine, not thread-affine.
(patchset #2 id:20001 of https://codereview.chromium.org/2591123004/ )

Reason for revert:
https://uberchromegw.corp.google.com/i/chromium.chromiumos/builders/Linux%20C...

The CL causes the browser_tests failure on Linux ChromiumOS Tests(dbg) 

Original issue's description:
> Document that HistoryBackend is sequence-affine, not thread-affine.
> 
> HistoryBackend methods must not be called concurrently and external
> synchronization is required between calls on different thread.
> However, the methods do not have to be called from a single thread.
> This CL documents this and adds DCHECKs to verify that
> HistoryBackend methods are called in sequence.
> 
> BUG=675800, 675631
> 
> Committed: https://crrev.com/0b0b5aab6e2474e0e758ca3777b07321e59a7463
> Cr-Commit-Position: refs/heads/master@{#440408}

TBR=sdefresne@chromium.org,fdoray@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=675800, 675631

Review-Url: https://codereview.chromium.org/2599803002
==========

to

==========
Revert of Document that HistoryBackend is sequence-affine, not thread-affine.
(patchset #2 id:20001 of https://codereview.chromium.org/2591123004/ )

Reason for revert:
https://uberchromegw.corp.google.com/i/chromium.chromiumos/builders/Linux%20C...

The CL causes the browser_tests failure on Linux ChromiumOS Tests(dbg)

Original issue's description:
> Document that HistoryBackend is sequence-affine, not thread-affine.
>
> HistoryBackend methods must not be called concurrently and external
> synchronization is required between calls on different thread.
> However, the methods do not have to be called from a single thread.
> This CL documents this and adds DCHECKs to verify that
> HistoryBackend methods are called in sequence.
>
> BUG=675800, 675631
>
> Committed: https://crrev.com/0b0b5aab6e2474e0e758ca3777b07321e59a7463
> Cr-Commit-Position: refs/heads/master@{#440408}

TBR=sdefresne@chromium.org,fdoray@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=675800, 675631

Committed: https://crrev.com/cc870ed0d9a16f478dd5e2f584ed19b749f2729f
Cr-Commit-Position: refs/heads/master@{#440441}
==========

[commit-bot: I haz the power, 2016-12-22 16:59:34]

Patchset 1 (id:??) landed as
https://crrev.com/cc870ed0d9a16f478dd5e2f584ed19b749f2729f
Cr-Commit-Position: refs/heads/master@{#440441}