Fix bug where removed (but not deleted) windows are not reflected in the tree properly

Fix bug where removed (but not deleted) windows are not reflected in the tree properly

When there are windows which are removed as children of some parent, and
they still exist, OnWindowDestroying is not called because the child window
was never destroyed. However, OnWindowTreeChanging is called, if
the target has an old_parent, aka the parent it is being removed from.
OnWindowTreeChanged is called if the target has a new_parent, aka the
parent it is being added to.

This CL removes nodes on OnWindowTreeChanging and adds them back in
OnWindowTreeChanged if necessary. Since we only want them to trigger once,
we check to see in either callback if the window that the callback is
being called on is the old_parent or the new_parent.

BUG=648701
Committed: https://crrev.com/f555669c992a0bf22b8994d6a6f5a3f27e9f32c4
Cr-Commit-Position: refs/heads/master@{#432366}

[Sarmad Hashmi, 2016-11-11 21:56:51]

The CQ bit was checked by mhashmi@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-11-11 21:57:17]

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

[Sarmad Hashmi, 2016-11-11 22:27:10]

The CQ bit was checked by mhashmi@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-11-11 22:28:01]

Dry run: 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, 2016-11-11 23:06:01]

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

[commit-bot: I haz the power, 2016-11-11 23:06:02]

Dry run: This issue passed the CQ dry run.

[Sarmad Hashmi, 2016-11-12 09:04:21]

PTAL sadrul@, trying to reland https://codereview.chromium.org/2476353002/

[Sarmad Hashmi, 2016-11-12 09:06:43]

mhashmi@chromium.org changed reviewers:
+ sadrul@chromium.org

[Sarmad Hashmi, 2016-11-12 09:06:43]

oops, forgot to add sadrul

[sadrul, 2016-11-16 00:18:00]

lgtm

[Sarmad Hashmi, 2016-11-16 00:19:34]

The CQ bit was checked by mhashmi@chromium.org

[commit-bot: I haz the power, 2016-11-16 00:20:02]

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, 2016-11-16 02:44:10]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-11-16 02:45:59]

Description was changed from

==========
Fix bug where removed (but not deleted) windows are not reflected in the tree
properly

When there are windows which are removed as children of some parent, and
they still exist, OnWindowDestroying is not called because the child window
was never destroyed. However, OnWindowTreeChanging is called, if
the target has an old_parent, aka the parent it is being removed from.
OnWindowTreeChanged is called if the target has a new_parent, aka the
parent it is being added to.

This CL removes nodes on OnWindowTreeChanging and adds them back in
OnWindowTreeChanged if necessary. Since we only want them to trigger once,
we check to see in either callback if the window that the callback is
being called on is the old_parent or the new_parent.

BUG=648701
==========

to

==========
Fix bug where removed (but not deleted) windows are not reflected in the tree
properly

When there are windows which are removed as children of some parent, and
they still exist, OnWindowDestroying is not called because the child window
was never destroyed. However, OnWindowTreeChanging is called, if
the target has an old_parent, aka the parent it is being removed from.
OnWindowTreeChanged is called if the target has a new_parent, aka the
parent it is being added to.

This CL removes nodes on OnWindowTreeChanging and adds them back in
OnWindowTreeChanged if necessary. Since we only want them to trigger once,
we check to see in either callback if the window that the callback is
being called on is the old_parent or the new_parent.

BUG=648701

Committed: https://crrev.com/f555669c992a0bf22b8994d6a6f5a3f27e9f32c4
Cr-Commit-Position: refs/heads/master@{#432366}
==========

[commit-bot: I haz the power, 2016-11-16 02:45:59]

Patchset 2 (id:??) landed as
https://crrev.com/f555669c992a0bf22b8994d6a6f5a3f27e9f32c4
Cr-Commit-Position: refs/heads/master@{#432366}

[Sarmad Hashmi, 2016-11-16 04:23:58]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/2506913002/ by mhashmi@chromium.org.

The reason for reverting is: SystemTrayTest.NullDefaultViewIsNotRecorded failing
(https://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%281%29/bui...).