Fix a null-deref in safe_browsing::dmg::UDIFParser::ParseBlkx.

Fix a null-deref in safe_browsing::dmg::UDIFParser::ParseBlkx.

The typechecking CFCast<T> returns null if the source type does not match
the destination type, but ParseBlkx was not checking the result for null.

BUG=654926
R=nparker@chromium.org

Committed: https://crrev.com/39ad5ff8e03689a22f387699b595952a7dc93fda
Cr-Commit-Position: refs/heads/master@{#429918}

[Robert Sesek, 2016-11-02 19:27:59]

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

[commit-bot: I haz the power, 2016-11-02 19:28:50]

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, 2016-11-02 19:48:59]

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

[commit-bot: I haz the power, 2016-11-02 19:49:00]

Dry run: This issue passed the CQ dry run.

[Robert Sesek, 2016-11-04 14:08:32]

Friendly ping

[Nathan Parker, 2016-11-04 16:16:19]

lgtm

[Robert Sesek, 2016-11-04 16:17:15]

The CQ bit was checked by rsesek@chromium.org

[commit-bot: I haz the power, 2016-11-04 16:17:50]

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, 2016-11-04 16:51:10]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-04 17:16:06]

Description was changed from

==========
Fix a null-deref in safe_browsing::dmg::UDIFParser::ParseBlkx.

The typechecking CFCast<T> returns null if the source type does not match
the destination type, but ParseBlkx was not checking the result for null.

BUG=654926
R=nparker@chromium.org
==========

to

==========
Fix a null-deref in safe_browsing::dmg::UDIFParser::ParseBlkx.

The typechecking CFCast<T> returns null if the source type does not match
the destination type, but ParseBlkx was not checking the result for null.

BUG=654926
R=nparker@chromium.org

Committed: https://crrev.com/39ad5ff8e03689a22f387699b595952a7dc93fda
Cr-Commit-Position: refs/heads/master@{#429918}
==========

[commit-bot: I haz the power, 2016-11-04 17:16:06]

Patchset 1 (id:??) landed as
https://crrev.com/39ad5ff8e03689a22f387699b595952a7dc93fda
Cr-Commit-Position: refs/heads/master@{#429918}