Fix leak of p2p sockets.

This was accidentally introduced in r580764.

Bug: 873785
Cq-Include-Trybots: luci.chromium.try:linux_mojo
Change-Id: Ie1e1aa9321f9863c5036a38d88cc7ca560127c00
Reviewed-on: https://chromium-review.googlesource.com/1175549
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583344}

services/network/p2p/socket_manager.cc

@@ -250,8 +250,8 @@ void P2PSocketManager::CreateSocket(P2PSocketType type,
     return;
   }
   std::unique_ptr<P2PSocket> socket(
-      P2PSocket::Create(nullptr /*this*/, std::move(client), std::move(request),
-                        type, url_request_context_->net_log(),
+      P2PSocket::Create(this, std::move(client), std::move(request), type,
+                        url_request_context_->net_log(),
                         proxy_resolving_socket_factory_.get(), &throttler_));
 
   if (!socket)