Revert of Removing references to webrtc::PortAllocatorFactoryInterface.

Revert of Removing references to webrtc::PortAllocatorFactoryInterface. (patchset #6 id:100001 of https://codereview.chromium.org/1500663003/ )

Reason for revert:
Seems to break build at http://build.chromium.org/p/chromium.linux/builders/Linux%20Builder%20%28dbg%29/builds/97032/steps/compile/logs/stdio

Original issue's description:
> Removing references to webrtc::PortAllocatorFactoryInterface.
> 
> Now using a new CreatePeerConnection method that takes a
> PortAllocator as input. This removes the need for some
> boilerplate code and code duplication between webrtc and chromium.
> It also fixes an issue with TURN candidate priorities.
> 
> BUG=webrtc:5209
> 
> Committed: https://crrev.com/ad868b5edf13e869e835b847078b4dcc8aa7cd0d
> Cr-Commit-Position: refs/heads/master@{#364544}

TBR=sergeyu@chromium.org,deadbeef@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:5209

[Marijn Kruisselbrink, 2015-12-11 01:15:24]

Created Revert of Removing references to webrtc::PortAllocatorFactoryInterface.

[Marijn Kruisselbrink, 2015-12-11 01:15:40]

The CQ bit was unchecked by mek@chromium.org