Create a new preference which disables UDP protocol for WebRTC

content/renderer/p2p/port_allocator.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_P2P_PORT_ALLOCATOR_H_
 #define CONTENT_RENDERER_P2P_PORT_ALLOCATOR_H_
 
 #include "third_party/webrtc/p2p/client/basicportallocator.h"
 #include "url/gurl.h"
 
@@ skipping 17 matching lines @@
       std::string server_address;
       int port;
       std::string transport_type;
       bool secure;
     };
 
     std::set<rtc::SocketAddress> stun_servers;
 
     std::vector<RelayServerConfig> relays;
 
-    // Disable TCP-based transport when set to true.
-    bool disable_tcp_transport;
+    // Disable TCP-based transport when set to false.

[juberti1, 2015/08/27 00:21:20]

This is somewhat confusing because enable_tcp_transport is subtly different than
enable_nonproxied_udp_transport. i.e., TCP transport set to false allows TCP
transport to relay, but UDP transport set to false doesn't allow UDP transport
to relay.

I think the key issue is the use of the word |transport|, since disabling
TcpPort is different than disabling *all UDP traffic*.

[pthatcher2, 2015/08/27 16:59:09]

That's a good point.  But since TCP to the relay would go through a proxy, we
could name it "enable_nonproxied_tcp" to match "enable_unproxied_udp", couldn't
we?  Then they would be consistent.

I agree with dropping the word "transport".  I don't like it.

+    bool enable_tcp_transport = true;
+
+    // Disable non-proxied UPD-based transport when set to false.

[juberti1, 2015/08/27 00:21:20]

UDP

+    bool enable_nonproxied_udp_transport = true;
 
     // Disable binding to individual NICs when set to false.
-    bool enable_multiple_routes;
+    bool enable_multiple_routes = true;
   };
 
   P2PPortAllocator(P2PSocketDispatcher* socket_dispatcher,
                    rtc::NetworkManager* network_manager,
                    rtc::PacketSocketFactory* socket_factory,
                    const Config& config,
                    const GURL& origin);
   ~P2PPortAllocator() override;
 
   cricket::PortAllocatorSession* CreateSessionInternal(
@@ skipping 28 matching lines @@
 
  private:
   P2PPortAllocator* allocator_;
 
   DISALLOW_COPY_AND_ASSIGN(P2PPortAllocatorSession);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_P2P_PORT_ALLOCATOR_H_