mac: Fix Yosemite crash while attempting to open multiple files.

mac: Fix Yosemite crash while attempting to open multiple files.

Attemping to open multiple files using the native Cocoa dialog causes a crash.
This CL inserts a safety check to work around it.

A Yosemite AppKit bug causes an NSWindowWillCloseNotification to be sent during
the -dealloc for a specific NSWindow. Any autoreleases sent to that window must
be drained before the window finishes -dealloc.

BUG=406944
Committed: https://crrev.com/e4dd0bd72be65f663b638e956916af1ca9d7d245
Cr-Commit-Position: refs/heads/master@{#295507}

[erikchen, 2014-09-18 17:39:52]

erikchen@chromium.org changed reviewers:
+ rsesek@chromium.org

[erikchen, 2014-09-18 17:39:52]

rsesek: Please review.

[Robert Sesek, 2014-09-18 17:45:39]

LGTM assuming you've tested this manually on 10.10

[erikchen, 2014-09-18 17:48:30]

yup. Crashes without this patch. Does not crash with patch.

[erikchen, 2014-09-18 17:49:05]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2014-09-18 17:51:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/582103002/1

[commit-bot: I haz the power, 2014-09-18 18:47:39]

Committed patchset #1 (id:1) as efa5f4e641ec5a1dfe90a9adeca6866a85c059b0

[commit-bot: I haz the power, 2014-09-18 18:48:24]

Patchset 1 (id:??) landed as
https://crrev.com/e4dd0bd72be65f663b638e956916af1ca9d7d245
Cr-Commit-Position: refs/heads/master@{#295507}