Adding IceConfig option to assume TURN/TURN candidate pairs will work.

webrtc/p2p/base/transport.h

Index: webrtc/p2p/base/transport.h
diff --git a/webrtc/p2p/base/transport.h b/webrtc/p2p/base/transport.h
index 9b6cf519f89106885da65972fd605d1f6beb1766..2c4c77a88162e22f524d86e9d1dc04a39df7b128 100644
--- a/webrtc/p2p/base/transport.h
+++ b/webrtc/p2p/base/transport.h
@@ -152,6 +152,8 @@ struct TransportStats {
 };
 
 // Information about ICE configuration.
+// TODO(deadbeef): Use rtc::Optional to represent unset values, instead of
+// -1.
 struct IceConfig {
   // The ICE connection receiving timeout value in milliseconds.
   int receiving_timeout = -1;
@@ -170,18 +172,27 @@ struct IceConfig {
   // (Default value is a little less than 2 * STRONG_PING_INTERVAL).
   int max_strong_interval = -1;
 
+  // If set to false, this means the ICE transport can expect TURN-to-TURN
+  // candidate pairs to work even before CreatePermission requests are sent
+  // to the TURN servers. This allows media to be sent earlier, without even
+  // requiring binding request/responses to verify that the connection works.
+  bool fully_relayed_createpermission_needed = true;

[pthatcher1, 2016/06/21 06:20:50]

I still think this needs to reflect that we are opting into "presume
writability" territory.  

"presume_writability_when_fully_relayed" or something like that.

[Taylor Brandstetter, 2016/06/22 00:37:07]

Done.

+
   IceConfig() {}
   IceConfig(int receiving_timeout_ms,
             int backup_connection_ping_interval,
             bool gather_continually,
             bool prioritize_most_likely_candidate_pairs,
-            int max_strong_interval_ms)
+            int max_strong_interval_ms,
+            bool fully_relayed_no_createpermission_needed)
       : receiving_timeout(receiving_timeout_ms),
         backup_connection_ping_interval(backup_connection_ping_interval),
         gather_continually(gather_continually),
         prioritize_most_likely_candidate_pairs(
             prioritize_most_likely_candidate_pairs),
-        max_strong_interval(max_strong_interval_ms) {}
+        max_strong_interval(max_strong_interval_ms),
+        fully_relayed_createpermission_needed(
+            fully_relayed_no_createpermission_needed) {}
 };
 
 bool BadTransportDescription(const std::string& desc, std::string* err_desc);