Revert of Reland v4 of Session refactor

Revert of Reland v4 of Session refactor (patchset #3 id:40001 of https://codereview.chromium.org/2683263002/ )

Reason for revert:
Still crashing. Likely due to sync nodes being reused across windows not being handled gracefully.

Original issue's description:
> Reland v4 of Session refactor
> 
> Previous review: https://codereview.chromium.org/2651583006/
> 
> Changes from previous review:
> - Deletes sync tab nodes with invalid tab ids
> - Adds support for gracefully ignoring tabs with the same tab id. It's
> unclear how this might happen, but we now log an error and silently
> ignore the tab, instead of crashing.
> - Adds some more checks to tests
> 
> TEST=SessionsSyncManagerTest.DuplicateTabIdFromNative, SessionsSyncManagerTest.MergeDeletesCorruptTabNodeId
> BUG=639009
> 
> Review-Url: https://codereview.chromium.org/2683263002
> Cr-Commit-Position: refs/heads/master@{#449677}
> Committed: https://chromium.googlesource.com/chromium/src/+/9e83363531256aad94ed2bec676bbca8d715fbe1

TBR=skym@chromium.org,pnoland@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=639009
Review-Url: https://codereview.chromium.org/2694963002
Cr-Commit-Position: refs/heads/master@{#450231}
Committed: https://chromium.googlesource.com/chromium/src/+/471807b6e3af01f221c48a2b96b8156763ca1db1

[Nicolas Zea, 2017-02-14 02:13:47]

The CQ bit was checked by zea@chromium.org

[Nicolas Zea, 2017-02-14 02:13:47]

Created Revert of Reland v4 of Session refactor

[commit-bot: I haz the power, 2017-02-14 02:14:59]

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, 2017-02-14 03:59:50]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1487038427575690, "parent_rev":
"436c4bebb1f31ef7246eb7747eccd9a812f09cf7", "commit_rev":
"471807b6e3af01f221c48a2b96b8156763ca1db1"}

[commit-bot: I haz the power, 2017-02-14 04:00:32]

Description was changed from

==========
Revert of Reland v4 of Session refactor (patchset #3 id:40001 of
https://codereview.chromium.org/2683263002/ )

Reason for revert:
Still crashing. Likely due to sync nodes being reused across windows not being
handled gracefully.

Original issue's description:
> Reland v4 of Session refactor
> 
> Previous review: https://codereview.chromium.org/2651583006/
> 
> Changes from previous review:
> - Deletes sync tab nodes with invalid tab ids
> - Adds support for gracefully ignoring tabs with the same tab id. It's
> unclear how this might happen, but we now log an error and silently
> ignore the tab, instead of crashing.
> - Adds some more checks to tests
> 
> TEST=SessionsSyncManagerTest.DuplicateTabIdFromNative,
SessionsSyncManagerTest.MergeDeletesCorruptTabNodeId
> BUG=639009
> 
> Review-Url: https://codereview.chromium.org/2683263002
> Cr-Commit-Position: refs/heads/master@{#449677}
> Committed:
https://chromium.googlesource.com/chromium/src/+/9e83363531256aad94ed2bec676b...

TBR=skym@chromium.org,pnoland@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=639009
==========

to

==========
Revert of Reland v4 of Session refactor (patchset #3 id:40001 of
https://codereview.chromium.org/2683263002/ )

Reason for revert:
Still crashing. Likely due to sync nodes being reused across windows not being
handled gracefully.

Original issue's description:
> Reland v4 of Session refactor
> 
> Previous review: https://codereview.chromium.org/2651583006/
> 
> Changes from previous review:
> - Deletes sync tab nodes with invalid tab ids
> - Adds support for gracefully ignoring tabs with the same tab id. It's
> unclear how this might happen, but we now log an error and silently
> ignore the tab, instead of crashing.
> - Adds some more checks to tests
> 
> TEST=SessionsSyncManagerTest.DuplicateTabIdFromNative,
SessionsSyncManagerTest.MergeDeletesCorruptTabNodeId
> BUG=639009
> 
> Review-Url: https://codereview.chromium.org/2683263002
> Cr-Commit-Position: refs/heads/master@{#449677}
> Committed:
https://chromium.googlesource.com/chromium/src/+/9e83363531256aad94ed2bec676b...

TBR=skym@chromium.org,pnoland@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=639009

Review-Url: https://codereview.chromium.org/2694963002
Cr-Commit-Position: refs/heads/master@{#450231}
Committed:
https://chromium.googlesource.com/chromium/src/+/471807b6e3af01f221c48a2b96b8...
==========

[commit-bot: I haz the power, 2017-02-14 04:00:33]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/471807b6e3af01f221c48a2b96b8...

[skym, 2017-02-14 18:01:07]

lgtm