Avoid unsafe usage of CancelIo() within Windows SyncSocket.

Avoid unsafe usage of CancelIo() within Windows SyncSocket.

The CancelIo() operation does not synchronously cancel IO operations,
we must wait for them to return before returning to avoid writes to
resources which may have already been destructed.

See this blog post for more information:

http://blogs.msdn.com/b/oldnewthing/archive/2011/02/02/10123392.aspx

BUG=413494
TEST=manual inspect of cancellation states.

Committed: https://crrev.com/3bdbb01600f8ca78609794c23f2f1c8410a78e98
Cr-Commit-Position: refs/heads/master@{#294946}

[DaleCurtis, 2014-09-12 21:40:34]

dalecurtis@chromium.org changed reviewers:
+ ajwong@chromium.org, rvargas@chromium.org

[DaleCurtis, 2014-09-12 21:40:34]

Due to the racy nature of this issue, I couldn't think of a way to write a test
for this.

[rvargas (doing something else), 2014-09-12 22:57:50]

lgtm

https://codereview.chromium.org/570713003/diff/1/base/sync_socket_win.cc
File base/sync_socket_win.cc (left):

https://codereview.chromium.org/570713003/diff/1/base/sync_socket_win.cc#oldc...
base/sync_socket_win.cc:163: count = 0;
Isn't this needed anymore? That said, not clearing count looks better to me.

[DaleCurtis, 2014-09-12 23:33:27]

Patchset #2 (id:20001) has been deleted

[DaleCurtis, 2014-09-12 23:34:10]

Patchset #2 (id:40001) has been deleted

[DaleCurtis, 2014-09-12 23:38:02]

https://codereview.chromium.org/570713003/diff/1/base/sync_socket_win.cc
File base/sync_socket_win.cc (left):

https://codereview.chromium.org/570713003/diff/1/base/sync_socket_win.cc#oldc...
base/sync_socket_win.cc:163: count = 0;
On 2014/09/12 22:57:50, rvargas wrote:
> Isn't this needed anymore? That said, not clearing count looks better to me.

Hmmm, I was going to say it doesn't matter, but then I looked at the clients and
they're not doing the right thing (harmlessly). The next patch set fixes one bad
instance and a faulty DCHECK.

[awong, 2014-09-15 18:21:51]

LGTM

[DaleCurtis, 2014-09-15 18:25:09]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-09-15 19:16:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/570713003/60001

[commit-bot: I haz the power, 2014-09-15 20:26:24]

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

[commit-bot: I haz the power, 2014-09-15 20:26:25]

Try jobs failed on following builders:
  linux_chromium_chromeos_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[DaleCurtis, 2014-09-15 22:56:58]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-09-15 23:32:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/570713003/60001

[commit-bot: I haz the power, 2014-09-16 00:44:13]

Committed patchset #2 (id:60001) as e40a88e3c5020ad27ca341741fe205a10cf59cbb

[commit-bot: I haz the power, 2014-09-16 00:46:07]

Patchset 2 (id:??) landed as
https://crrev.com/3bdbb01600f8ca78609794c23f2f1c8410a78e98
Cr-Commit-Position: refs/heads/master@{#294946}