MacViews: Retain non-Widget parent NSWindows, as well as the anchor NSView.

MacViews: Retain non-Widget parent NSWindows, as well as the anchor NSView.

Linking against the 10.6 SDK tickles an AppKit bug that causes a parent
NSWindow to disappear from screen when it has a child window that
closes.

NativeWidgetMac tries to ensure windows are only closed when they have
no parent window. However, for child Widgets with non-Widget parents, if
the "anchor" NSView used to create the dialog was removed from its own
view hierarchy while the child dialog is still alive, this step was
being skipped.

Specifically, this happens for tab-modal dialogs that have a fade out
animation that can outlast the NSView it was initially anchored off.

Fix by retaining the NSWindow parent when the parent-child relationship
is initially created.

BUG=485854
Committed: https://crrev.com/ff8d9e06d49636d3729192dbcf791469727a264d
Cr-Commit-Position: refs/heads/master@{#333637}

[tapted, 2015-06-09 08:15:41]

tapted@chromium.org changed reviewers:
+ jackhou@chromium.org

[tapted, 2015-06-09 08:21:31]

Hi Jack, please take a look

(also i've totally been forgetting to +cc mac-views-reviews@.. doh).

[jackhou1, 2015-06-10 00:41:02]

lgtm

[tapted, 2015-06-10 00:51:36]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2015-06-10 00:53:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1169063002/1

[commit-bot: I haz the power, 2015-06-10 01:26:48]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-10 01:28:40]

Patchset 1 (id:??) landed as
https://crrev.com/ff8d9e06d49636d3729192dbcf791469727a264d
Cr-Commit-Position: refs/heads/master@{#333637}