MergeNetworkList can't group address under the same interface

IpcNetworkManager in renderer/p2p didn't specify the right network prefix,
which prevent grouping mechanism in MergeNetworkList from working.

The end result is that each Network after MergeNetworkList contains only 1 ip address. With this change, the grouping will happen correctly. WebRTC has logic to only retrieve single IP from each network for connectivity check already.

This CL is a dup of https://codereview.chromium.org/536133003/ which was created under the wrong identity.
BUG=

Committed: https://crrev.com/bb4f3cc4fce55e68f3a4a63e541bc7ec62175aa4
Cr-Commit-Position: refs/heads/master@{#294912}

[guoweis2, 2014-09-15 20:01:14]

guoweis@google.com changed reviewers:
+ davidben@chromium.org, guoweis@google.com, sergeyu@chromium.org,
wfh@chromium.org

[guoweis2, 2014-09-15 20:01:15]

Hi,

I incorrectly used my webrtc account to create the previous CL and failed the
presubmit check by CQ. Could you just rubber lgtm for me again?

Sorry for the inconvenience. 

Thanks,
Guowei

[Sergey Ulanov, 2014-09-15 20:06:49]

lgtm

[Will Harris, 2014-09-15 20:07:54]

On 2014/09/15 20:01:15, guoweis2 wrote:
> Hi,
> 
> I incorrectly used my webrtc account to create the previous CL and failed the
> presubmit check by CQ. Could you just rubber lgtm for me again?
> 
> Sorry for the inconvenience. 
> 
> Thanks,
> Guowei

Can you make the subject/description of this CL match the other one, and also
refer to the previous CL here so we have a record of the previous discussion.

Otherwise, LGTM for p2p_messages.h

[davidben, 2014-09-15 20:34:38]

lgtm

[guoweis2, 2014-09-15 20:36:23]

The CQ bit was checked by guoweis@google.com

[commit-bot: I haz the power, 2014-09-15 20:37:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/565773003/1

[commit-bot: I haz the power, 2014-09-15 23:07:31]

Committed patchset #1 (id:1) as b8c81d0b2cbd8f9d2e94cd68273eaae129a7dff7

[commit-bot: I haz the power, 2014-09-15 23:16:16]

Patchset 1 (id:??) landed as
https://crrev.com/bb4f3cc4fce55e68f3a4a63e541bc7ec62175aa4
Cr-Commit-Position: refs/heads/master@{#294912}