Prevent ~StickyKeysOverlay() from calling back into StickyKeysOverlay via the animator.

Prevent ~StickyKeysOverlay() from calling back into StickyKeysOverlay via the animator.

The animator calls StickyKeysOverlay::OnLayerAnimationEnded() during the
destruction of |overlay_widget_|, which dereferences overlay_widget_.
However, unique_ptr in libc++ (which we want to replace scoped_ptr with)
sets its value to nullptr before deleting the object, resulting in a
nullptr dereference.

BUG=535321
Committed: https://crrev.com/4ce7724a1dbe5d73f3dd19bf74e60d18189333a1
Cr-Commit-Position: refs/heads/master@{#354409}

[Anand Mistry (off Chromium), 2015-10-13 06:56:48]

amistry@chromium.org changed reviewers:
+ tengs@chromium.org

[Anand Mistry (off Chromium), 2015-10-13 21:45:12]

I should mention, the stack trace that leads to this is:
#3 0x0000004823c9 base::internal::scoped_ptr_impl<>::get()
#4 0x0000004f1d05 scoped_ptr<>::operator ??::internal::scoped_ptr_impl<>()
#5 0x000003073664 ash::StickyKeysOverlay::OnLayerAnimationEnded()
#6 0x000004044101 ui::LayerAnimationSequence::NotifyEnded()
#7 0x00000404440d ui::LayerAnimationSequence::ProgressToEnd()
#8 0x00000404c6ef ui::LayerAnimator::ProgressAnimationToEnd()
#9 0x00000404c050 ui::LayerAnimator::FinishAnimation()
#10 0x00000404cf79 ui::LayerAnimator::StopAnimatingInternal()
#11 0x000000591627 ui::LayerAnimator::StopAnimating()
#12 0x000004032a5f ui::Layer::CompleteAllAnimations()
#13 0x000003ffe9b8 aura::Window::~Window()
#14 0x000003fff569 aura::Window::~Window()
#15 0x000001a90d92 views::NativeWidgetAura::CloseNow()
#16 0x000001a93c71 views::NativeWidgetAura::~NativeWidgetAura()
#17 0x000001a93e29 views::NativeWidgetAura::~NativeWidgetAura()
#18 0x000001a6f387 views::Widget::~Widget()
#19 0x000001a6f639 views::Widget::~Widget()
#20 0x00000047477f base::DefaultDeleter<>::operator()()
#21 0x000000474742 base::internal::scoped_ptr_impl<>::~scoped_ptr_impl()
#22 0x0000008bf7a5 scoped_ptr<>::~scoped_ptr()
#23 0x000003073211 ash::StickyKeysOverlay::~StickyKeysOverlay()
#24 0x000003073249 ash::StickyKeysOverlay::~StickyKeysOverlay()
#25 0x00000059f60f base::DefaultDeleter<>::operator()()
#26 0x000001a77379 base::internal::scoped_ptr_impl<>::reset()
#27 0x000001a74e9d scoped_ptr<>::reset()
#28 0x000003070325 ash::StickyKeysController::Enable()

[Tim Song, 2015-10-14 23:48:38]

Sorry for the delay. LGTM.

[Anand Mistry (off Chromium), 2015-10-15 00:04:20]

The CQ bit was checked by amistry@chromium.org

[commit-bot: I haz the power, 2015-10-15 00:05:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1398403005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1398403005/1

[commit-bot: I haz the power, 2015-10-15 01:23:10]

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

[commit-bot: I haz the power, 2015-10-15 01:23:11]

Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[Anand Mistry (off Chromium), 2015-10-15 03:29:40]

The CQ bit was checked by amistry@chromium.org

[commit-bot: I haz the power, 2015-10-15 03:29:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1398403005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1398403005/1

[commit-bot: I haz the power, 2015-10-15 04:46:42]

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

[commit-bot: I haz the power, 2015-10-15 04:46:43]

Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[Anand Mistry (off Chromium), 2015-10-15 23:20:27]

The CQ bit was checked by amistry@chromium.org

[commit-bot: I haz the power, 2015-10-15 23:20:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1398403005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1398403005/1

[commit-bot: I haz the power, 2015-10-16 00:04:28]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-16 00:05:20]

Patchset 1 (id:??) landed as
https://crrev.com/4ce7724a1dbe5d73f3dd19bf74e60d18189333a1
Cr-Commit-Position: refs/heads/master@{#354409}