[ash-md] Corrects a crash when a window is destroyed after leaving overview

[ash-md] Corrects a crash when a window is closed after leaving overview

Exiting overview mode may leave overview header widget still animating.
It is important not to attempt any window manipulation such as
re-stacking when the animation completes because the affected windows
may be gone by then.

BUG=646350
TEST=WindowSelectorTest.SafeToDestroyWindowDuringAnimation

Committed: https://crrev.com/81e77929734c8d7d02e9c8dfb2673667b055accb
Cr-Commit-Position: refs/heads/master@{#418780}

[varkha, 2016-09-15 00:33:33]

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

[commit-bot: I haz the power, 2016-09-15 00:34:22]

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

[varkha, 2016-09-15 00:37:01]

varkha@chromium.org changed reviewers:
+ sky@chromium.org

[varkha, 2016-09-15 00:37:02]

sky@, could you please take a look? Since I have missed this in the review I
think this required a test.
I have also made sure again that it should not be possible to get into this bad
state while WindowSelectorItem is still active (i.e. while entering overview or
during overview). In those cases |item_window_| would have already been properly
reset.

[commit-bot: I haz the power, 2016-09-15 01:00:36]

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

[commit-bot: I haz the power, 2016-09-15 01:00:37]

Dry run: Try jobs failed on following builders:
  win_chromium_x64_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[varkha, 2016-09-15 02:07:38]

Patchset #1 (id:1) has been deleted

[varkha, 2016-09-15 02:07:45]

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

[commit-bot: I haz the power, 2016-09-15 02:08:01]

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, 2016-09-15 02:42:30]

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

[commit-bot: I haz the power, 2016-09-15 02:42:30]

Dry run: This issue passed the CQ dry run.

[sky, 2016-09-15 03:01:00]

LGTM

https://codereview.chromium.org/2337383003/diff/20001/ash/wm/overview/window_...
File ash/wm/overview/window_selector_unittest.cc (right):

https://codereview.chromium.org/2337383003/diff/20001/ash/wm/overview/window_...
ash/wm/overview/window_selector_unittest.cc:1312: ASSERT_TRUE(!!animation);
Double negatives are hard to read. ASSERT_NE(nullptr, animation) states
intention much better.

[varkha, 2016-09-15 03:54:18]

Thanks for quickly looking at this!

https://codereview.chromium.org/2337383003/diff/20001/ash/wm/overview/window_...
File ash/wm/overview/window_selector_unittest.cc (right):

https://codereview.chromium.org/2337383003/diff/20001/ash/wm/overview/window_...
ash/wm/overview/window_selector_unittest.cc:1312: ASSERT_TRUE(!!animation);
On 2016/09/15 03:01:00, sky wrote:
> Double negatives are hard to read. ASSERT_NE(nullptr, animation) states
> intention much better.

Done.

[varkha, 2016-09-15 03:54:25]

The CQ bit was checked by varkha@chromium.org

[varkha, 2016-09-15 03:54:25]

The patchset sent to the CQ was uploaded after l-g-t-m from sky@chromium.org
Link to the patchset: https://codereview.chromium.org/2337383003/#ps40001
(title: "[ash-md] Corrects a crash when a window is destroyed after leaving
overview (nits)")

[commit-bot: I haz the power, 2016-09-15 03:54:50]

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, 2016-09-15 04:27:51]

Committed patchset #2 (id:40001)

[commit-bot: I haz the power, 2016-09-15 04:30:23]

Description was changed from

==========
[ash-md] Corrects a crash when a window is closed after leaving overview

Exiting overview mode may leave overview header widget still animating.
It is important not to attempt any window manipulation such as
re-stacking when the animation completes because the affected windows
may be gone by then.

BUG=646350
TEST=WindowSelectorTest.SafeToDestroyWindowDuringAnimation
==========

to

==========
[ash-md] Corrects a crash when a window is closed after leaving overview

Exiting overview mode may leave overview header widget still animating.
It is important not to attempt any window manipulation such as
re-stacking when the animation completes because the affected windows
may be gone by then.

BUG=646350
TEST=WindowSelectorTest.SafeToDestroyWindowDuringAnimation

Committed: https://crrev.com/81e77929734c8d7d02e9c8dfb2673667b055accb
Cr-Commit-Position: refs/heads/master@{#418780}
==========

[commit-bot: I haz the power, 2016-09-15 04:30:24]

Patchset 2 (id:??) landed as
https://crrev.com/81e77929734c8d7d02e9c8dfb2673667b055accb
Cr-Commit-Position: refs/heads/master@{#418780}