Add a null check for last committed entry in ClassifyNavigation.

Add a null check for last committed entry in ClassifyNavigation.

BUG=640429
TEST=No more ClassifyNavigation crashes.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Committed: https://crrev.com/5eb00a5f409b89783ee1685a7c59786727d31aeb
Cr-Commit-Position: refs/heads/master@{#413973}

[Charlie Reis, 2016-08-24 00:47:08]

Description was changed from

==========
Add a null check for last committed entry in ClassifyNavigation.

BUG=640429
TEST=No more ClassifyNavigation crashes.
==========

to

==========
Add a null check for last committed entry in ClassifyNavigation.

BUG=640429
TEST=No more ClassifyNavigation crashes.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation
==========

[Charlie Reis, 2016-08-24 00:47:40]

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

[commit-bot: I haz the power, 2016-08-24 00:48:14]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Charlie Reis, 2016-08-24 00:53:58]

creis@chromium.org changed reviewers:
+ nasko@chromium.org

[Charlie Reis, 2016-08-24 00:53:59]

Nasko: Mind reviewing?  I stumbled across these crash reports, which we should
prevent.

(I wasn't able to find repro steps to write a test, since just omitting the
first navigation from the NavigationTypeClassification_EmptyGURL test didn't
repro the crash.)

[commit-bot: I haz the power, 2016-08-24 02:04:01]

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

[commit-bot: I haz the power, 2016-08-24 02:04:02]

Dry run: Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[nasko, 2016-08-24 03:02:51]

LGTM

[Charlie Reis, 2016-08-24 03:03:25]

The CQ bit was checked by creis@chromium.org

[commit-bot: I haz the power, 2016-08-24 03:04:56]

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, 2016-08-24 03:50:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-24 03:52:14]

Description was changed from

==========
Add a null check for last committed entry in ClassifyNavigation.

BUG=640429
TEST=No more ClassifyNavigation crashes.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation
==========

to

==========
Add a null check for last committed entry in ClassifyNavigation.

BUG=640429
TEST=No more ClassifyNavigation crashes.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Committed: https://crrev.com/5eb00a5f409b89783ee1685a7c59786727d31aeb
Cr-Commit-Position: refs/heads/master@{#413973}
==========

[commit-bot: I haz the power, 2016-08-24 03:52:15]

Patchset 1 (id:??) landed as
https://crrev.com/5eb00a5f409b89783ee1685a7c59786727d31aeb
Cr-Commit-Position: refs/heads/master@{#413973}