Fix PepperPortAllocatorSession to initialize callback_factory_.

Fix PepperPortAllocatorSession to initialize callback_factory_.

After crrev.com/368701 PepperPortAllocatorSession constructor wasn't
initializing calllback_factory_ properly, so the plugin was crashing.

BUG=576985
Committed: https://crrev.com/4f5bacb7eaade57cc8f6164478f026519adb6907
Cr-Commit-Position: refs/heads/master@{#369245}

[Sergey Ulanov, 2016-01-13 18:06:37]

sergeyu@chromium.org changed reviewers:
+ kelvinp@chromium.org

[Jamie, 2016-01-13 18:13:04]

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

[Jamie, 2016-01-13 18:13:04]

lgtm

[kelvinp, 2016-01-13 18:41:01]

lgtm

[Sergey Ulanov, 2016-01-13 19:07:05]

The CQ bit was checked by sergeyu@chromium.org

[commit-bot: I haz the power, 2016-01-13 19:07:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1584883002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1584883002/1

[commit-bot: I haz the power, 2016-01-13 19:53:31]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-01-13 19:54:21]

Description was changed from

==========
Fix PepperPortAllocatorSession to initialize callback_factory_.

After crrev.com/368701 PepperPortAllocatorSession constructor wasn't
initializing calllback_factory_ properly, so the plugin was crashing.

BUG=576985
==========

to

==========
Fix PepperPortAllocatorSession to initialize callback_factory_.

After crrev.com/368701 PepperPortAllocatorSession constructor wasn't
initializing calllback_factory_ properly, so the plugin was crashing.

BUG=576985

Committed: https://crrev.com/4f5bacb7eaade57cc8f6164478f026519adb6907
Cr-Commit-Position: refs/heads/master@{#369245}
==========

[commit-bot: I haz the power, 2016-01-13 19:54:22]

Patchset 1 (id:??) landed as
https://crrev.com/4f5bacb7eaade57cc8f6164478f026519adb6907
Cr-Commit-Position: refs/heads/master@{#369245}