Mac: Disconnect DesktopMediaPicker window from the parent before closing

Mac: Disconnect DesktopMediaPicker window from the parent before closing

The window wasn't removing itself from the parent's children list, which
causes linked bug with some versions of Cocoa.

BUG=331058
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=243212

[Sergey Ulanov, 2014-01-06 19:38:36]

Official Chrome builds are compiled with a different SDK version (10.6), that's
why I didn't see this issue when testing my change that caused the bug
(https://codereview.chromium.org/120253002).

[dcaiafa, 2014-01-06 19:44:16]

lgtm

[Mark Mentovai, 2014-01-06 20:03:16]

LGTM

As I recall, this is exactly what I asked about during the original review…

[Sergey Ulanov, 2014-01-06 20:14:37]

On 2014/01/06 20:03:16, Mark Mentovai wrote:
> LGTM
> 
> As I recall, this is exactly what I asked about during the original review…

That's right. Daniel was concerned about it too. I was testing with 10.8 SDK and
this change didn't make any difference with 10.8 (it looks like NSWindow removes
closed children automatically only in newer versions of Cococa).

[commit-bot: I haz the power, 2014-01-06 20:16:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sergeyu@chromium.org/125133006/30001

[commit-bot: I haz the power, 2014-01-07 00:15:02]

Change committed as 243212