Fix crash in ui::ClipboardMac::ReadAvailableTypes.

Fix crash in ui::ClipboardMac::ReadAvailableTypes.

+[NSPasteboard generalPasteboard] has always been able to return nil if the
common pasteboard storage area is full. In macOS 10.12, +[NSImage
canInitWithPasteboard:] will segfault if passed a nil pasteboard. This CL adds
the appropriate conditionals.

BUG=630543
Committed: https://crrev.com/a1bf19009e91a8356d3371c457f87abc66a11c2d
Cr-Commit-Position: refs/heads/master@{#411081}

[erikchen, 2016-08-09 23:13:40]

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

[erikchen, 2016-08-09 23:14:11]

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

[erikchen, 2016-08-09 23:14:12]

ccameron: Please review.

[commit-bot: I haz the power, 2016-08-09 23:14:38]

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, 2016-08-10 00:20:08]

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

[commit-bot: I haz the power, 2016-08-10 00:20:09]

Dry run: This issue passed the CQ dry run.

[dcheng, 2016-08-10 14:28:34]

dcheng@chromium.org changed reviewers:
+ dcheng@chromium.org

[dcheng, 2016-08-10 14:28:34]

https://codereview.chromium.org/2227083003/diff/1/ui/base/clipboard/clipboard...
File ui/base/clipboard/clipboard_mac.mm (right):

https://codereview.chromium.org/2227083003/diff/1/ui/base/clipboard/clipboard...
ui/base/clipboard/clipboard_mac.mm:353: if (!pb)
How come this one needs a null check too?

[erikchen, 2016-08-10 16:35:59]

https://codereview.chromium.org/2227083003/diff/1/ui/base/clipboard/clipboard...
File ui/base/clipboard/clipboard_mac.mm (right):

https://codereview.chromium.org/2227083003/diff/1/ui/base/clipboard/clipboard...
ui/base/clipboard/clipboard_mac.mm:353: if (!pb)
On 2016/08/10 14:28:34, dcheng (OOO Aug 1 - Aug 11) wrote:
> How come this one needs a null check too?

Unnecessary, removed.

[ccameron, 2016-08-10 16:41:49]

lgtm

[erikchen, 2016-08-10 16:42:14]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2016-08-10 16:42:47]

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, 2016-08-10 17:51:05]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-08-10 17:54:16]

Description was changed from

==========
Fix crash in ui::ClipboardMac::ReadAvailableTypes.

+[NSPasteboard generalPasteboard] has always been able to return nil if the
common pasteboard storage area is full. In macOS 10.12, +[NSImage
canInitWithPasteboard:] will segfault if passed a nil pasteboard. This CL adds
the appropriate conditionals.

BUG=630543
==========

to

==========
Fix crash in ui::ClipboardMac::ReadAvailableTypes.

+[NSPasteboard generalPasteboard] has always been able to return nil if the
common pasteboard storage area is full. In macOS 10.12, +[NSImage
canInitWithPasteboard:] will segfault if passed a nil pasteboard. This CL adds
the appropriate conditionals.

BUG=630543

Committed: https://crrev.com/a1bf19009e91a8356d3371c457f87abc66a11c2d
Cr-Commit-Position: refs/heads/master@{#411081}
==========

[commit-bot: I haz the power, 2016-08-10 17:54:18]

Patchset 2 (id:??) landed as
https://crrev.com/a1bf19009e91a8356d3371c457f87abc66a11c2d
Cr-Commit-Position: refs/heads/master@{#411081}