Mac File Dialogs: Fix crash due to adding nil value to an NSMutableSet.

Mac File Dialogs: Fix crash due to adding nil value to an NSMutableSet.

Crash reports beginning from Chrome V48 suggest that CreateUTIFromExtension may
return nil. This causes a crash when the uti string is added to the
NSMutableSet which holds the uti strings corresponding to the extension
dropdown. This CL does a nil check before adding the string to the set, which
should prevent the crash.

BUG=630101
Committed: https://crrev.com/d338ac5a24ba53dae98c779346e371c29f02ebed
Cr-Commit-Position: refs/heads/master@{#407114}

[karandeepb, 2016-07-21 05:29:52]

Description was changed from

==========
---

BUG=
==========

to

==========
Mac File Dialogs: Fix crash due to adding nil value to an NSMutableSet.

Crash reports beginning from Chrome V48 suggest that CreateUTIFromExtension may
return nil. This causes a crash when the uti string is added to the 
NSMutableSet which holds the uti strings corresponding to the extension 
dropdown. This CL does a nil check before adding the string to the set, which
should prevent the crash.

BUG=630101
==========

[karandeepb, 2016-07-21 05:37:47]

karandeepb@chromium.org changed reviewers:
+ avi@chromium.org

[karandeepb, 2016-07-21 05:37:47]

PTAL avi@. Thanks.

[Avi (use Gerrit), 2016-07-21 14:25:20]

LGTM with request.

https://codereview.chromium.org/2164223003/diff/1/ui/shell_dialogs/select_fil...
File ui/shell_dialogs/select_file_dialog_mac.mm (right):

https://codereview.chromium.org/2164223003/diff/1/ui/shell_dialogs/select_fil...
ui/shell_dialogs/select_file_dialog_mac.mm:32: kUTTagClassFilenameExtension,
ext_cf.get(), NULL);
The documentation
(https://developer.apple.com/library/mac/documentation/MobileCoreServices/Refe...)
says that this should only return NULL if the tag class is unknown, not if the
tag is unknown.

Please file a radar with Apple.

[karandeepb, 2016-07-22 09:17:16]

https://codereview.chromium.org/2164223003/diff/1/ui/shell_dialogs/select_fil...
File ui/shell_dialogs/select_file_dialog_mac.mm (right):

https://codereview.chromium.org/2164223003/diff/1/ui/shell_dialogs/select_fil...
ui/shell_dialogs/select_file_dialog_mac.mm:32: kUTTagClassFilenameExtension,
ext_cf.get(), NULL);
On 2016/07/21 14:25:20, Avi wrote:
> The documentation
>
(https://developer.apple.com/library/mac/documentation/MobileCoreServices/Refe...)
> says that this should only return NULL if the tag class is unknown, not if the
> tag is unknown.
> 
> Please file a radar with Apple.

Filed rdar://27490414.  Although can't reproduce this manually and this is a
fairly rare crash.

[karandeepb, 2016-07-22 09:17:36]

The CQ bit was checked by karandeepb@chromium.org

[commit-bot: I haz the power, 2016-07-22 09:18:03]

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, 2016-07-22 09:48:02]

Description was changed from

==========
Mac File Dialogs: Fix crash due to adding nil value to an NSMutableSet.

Crash reports beginning from Chrome V48 suggest that CreateUTIFromExtension may
return nil. This causes a crash when the uti string is added to the 
NSMutableSet which holds the uti strings corresponding to the extension 
dropdown. This CL does a nil check before adding the string to the set, which
should prevent the crash.

BUG=630101
==========

to

==========
Mac File Dialogs: Fix crash due to adding nil value to an NSMutableSet.

Crash reports beginning from Chrome V48 suggest that CreateUTIFromExtension may
return nil. This causes a crash when the uti string is added to the 
NSMutableSet which holds the uti strings corresponding to the extension 
dropdown. This CL does a nil check before adding the string to the set, which
should prevent the crash.

BUG=630101
==========

[commit-bot: I haz the power, 2016-07-22 09:48:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-22 09:49:32]

Description was changed from

==========
Mac File Dialogs: Fix crash due to adding nil value to an NSMutableSet.

Crash reports beginning from Chrome V48 suggest that CreateUTIFromExtension may
return nil. This causes a crash when the uti string is added to the 
NSMutableSet which holds the uti strings corresponding to the extension 
dropdown. This CL does a nil check before adding the string to the set, which
should prevent the crash.

BUG=630101
==========

to

==========
Mac File Dialogs: Fix crash due to adding nil value to an NSMutableSet.

Crash reports beginning from Chrome V48 suggest that CreateUTIFromExtension may
return nil. This causes a crash when the uti string is added to the
NSMutableSet which holds the uti strings corresponding to the extension
dropdown. This CL does a nil check before adding the string to the set, which
should prevent the crash.

BUG=630101

Committed: https://crrev.com/d338ac5a24ba53dae98c779346e371c29f02ebed
Cr-Commit-Position: refs/heads/master@{#407114}
==========

[commit-bot: I haz the power, 2016-07-22 09:49:33]

Patchset 1 (id:??) landed as
https://crrev.com/d338ac5a24ba53dae98c779346e371c29f02ebed
Cr-Commit-Position: refs/heads/master@{#407114}

[Avi (use Gerrit), 2016-07-22 15:47:55]

On 2016/07/22 09:17:16, karandeepb wrote:
>
https://codereview.chromium.org/2164223003/diff/1/ui/shell_dialogs/select_fil...
> File ui/shell_dialogs/select_file_dialog_mac.mm (right):
> 
>
https://codereview.chromium.org/2164223003/diff/1/ui/shell_dialogs/select_fil...
> ui/shell_dialogs/select_file_dialog_mac.mm:32: kUTTagClassFilenameExtension,
> ext_cf.get(), NULL);
> On 2016/07/21 14:25:20, Avi wrote:
> > The documentation
> >
>
(https://developer.apple.com/library/mac/documentation/MobileCoreServices/Refe...)
> > says that this should only return NULL if the tag class is unknown, not if
the
> > tag is unknown.
> > 
> > Please file a radar with Apple.
> 
> Filed rdar://27490414.  Although can't reproduce this manually and this is a
> fairly rare crash.

Awesome; can you add that link to the code in the comment?