Fix callback access in Pepper's UDP socket resource

Fix callback access in Pepper's UDP socket resource

BUG=452249
Committed: https://crrev.com/89f28c88b7c9fe13c9b723b19c5c9dd189521d81
Cr-Commit-Position: refs/heads/master@{#313568}

[elijahtaylor1, 2015-01-28 04:59:08]

elijahtaylor@chromium.org changed reviewers:
+ bbudge@chromium.org

[elijahtaylor1, 2015-01-28 05:01:08]

PTAL.  Under some circumstances, this can lead to a renderer crash because the
front of the queue is assigned when it has already been destroyed and the queue
is empty.

[bbudge, 2015-01-28 18:07:31]

LGTM w/comment

https://codereview.chromium.org/881203002/diff/1/ppapi/proxy/udp_socket_resou...
File ppapi/proxy/udp_socket_resource_base.cc (right):

https://codereview.chromium.org/881203002/diff/1/ppapi/proxy/udp_socket_resou...
ppapi/proxy/udp_socket_resource_base.cc:323: if (sendto_callbacks_.empty())
Add a comment that this could happen when the socket has been closed.

[elijahtaylor1, 2015-01-28 18:18:01]

The CQ bit was checked by elijahtaylor@chromium.org

[commit-bot: I haz the power, 2015-01-28 18:19:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/881203002/20001

[commit-bot: I haz the power, 2015-01-28 20:12:10]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-28 20:13:03]

Patchset 2 (id:??) landed as
https://crrev.com/89f28c88b7c9fe13c9b723b19c5c9dd189521d81
Cr-Commit-Position: refs/heads/master@{#313568}