Correctly fix a bug when a QUIC session is closed during the call to

Correctly fix a bug when a QUIC session is closed during the call to
InitializeSession. This seems to be able to happen if too much time
elapses between the call to the constructor and the call to InitializeSession.

This fixes the fix from https://codereview.chromium.org/560913002

BUG=399147
Committed: https://crrev.com/eaa3d4faf6ed16c97f3e4d7bc02e816960c6befe
Cr-Commit-Position: refs/heads/master@{#295601}

[Ryan Hamilton, 2014-09-18 19:48:13]

rch@chromium.org changed reviewers:
+ rtenneti@chromium.org

[ramant (doing other things), 2014-09-18 21:02:40]

lgtm

[Ryan Hamilton, 2014-09-18 21:03:16]

The CQ bit was checked by rch@chromium.org

[commit-bot: I haz the power, 2014-09-18 21:04:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/579533003/20001

[Ryan Hamilton, 2014-09-18 22:38:57]

The CQ bit was unchecked by rch@chromium.org

[Ryan Hamilton, 2014-09-18 22:40:43]

The CQ bit was checked by rch@chromium.org

[commit-bot: I haz the power, 2014-09-18 22:41:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/579533003/20001

[commit-bot: I haz the power, 2014-09-18 23:36:29]

Committed patchset #2 (id:20001) as b1b3ce693c9eac21c7d7d21ae09b53cc9b4103c1

[commit-bot: I haz the power, 2014-09-18 23:37:04]

Patchset 2 (id:??) landed as
https://crrev.com/eaa3d4faf6ed16c97f3e4d7bc02e816960c6befe
Cr-Commit-Position: refs/heads/master@{#295601}