UDP NetConnectivity tests - added read/write states to handle pending

UDP NetConnectivity tests - added read/write states to handle pending
read/writes.

- During read(), if socket_ returns ERR_IO_PENDING, set read_state_ to
  READ_STATE_PENDING and avoid further read() until OnReadComplete
  is called.

- During write(), if socket_ returns ERR_IO_PENDING, set write_state_
  to WRITE_STATE_ABORT_IN_PROGRESS. Cancel the pending read() and
  write(). Stop performing any more tests.

This change fixes use after free of write_buffer_.

BUG=273917
R=jar@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=240153

[ramant (doing other things), 2013-12-09 00:33:42]

Hi Jim,
  Implemented what we had discussed Friday on how to handle pending
reads/writes. Would appreciate if you could take a look.

thanks
raman

[ramant (doing other things), 2013-12-09 22:37:45]

Hi Jim,
  Added a new histogram to track tests being stopped due to pending writes.
Could you please take another look?

thanks
raman

[jar (doing other things), 2013-12-09 22:56:57]

lgtm

[commit-bot: I haz the power, 2013-12-09 23:06:54]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rtenneti@chromium.org/102993007/70001

[ramant (doing other things), 2013-12-10 22:40:50]

Hi Jim,
  Added new histograms. Would appreciate if you could take another look.

thanks
raman

[jar (doing other things), 2013-12-10 22:48:44]

https://codereview.chromium.org/102993007/diff/90001/tools/metrics/histograms...
File tools/metrics/histograms/histograms.xml (left):

https://codereview.chromium.org/102993007/diff/90001/tools/metrics/histograms...
tools/metrics/histograms/histograms.xml:31896:
name="NetConnectivity4.StartPacket.Sent21.Success.RTT.Packet20"/>
Why are there only 2 for NetConnectivity4?

I think you can get away with just adding a few lines to:

<fieldtrial name="NetConnectivity4PacketReceives" separator=".">

It has this giant list for NetConnectivity4.

WDYT?

In general, we should only have entries where we see NetConnectivity4.

[jar (doing other things), 2013-12-10 23:56:07]

Ok... thanks for the pointers into the existing xml file.

LGTM

[commit-bot: I haz the power, 2013-12-10 23:57:01]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rtenneti@chromium.org/102993007/90001

[commit-bot: I haz the power, 2013-12-11 04:26:09]

Retried try job too often on win_rel for step(s) browser_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2013-12-11 17:53:51]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rtenneti@chromium.org/102993007/90001

[commit-bot: I haz the power, 2013-12-11 19:32:50]

Change committed as 240153