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..07c2a99789dd2fe0f25b960cfd84b4608f22933f 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 turn_to_turn_createpermission_needed = true;

[pthatcher1, 2016/06/15 19:12:47]

I was thinking of a name like presume_connected_fully_relayed_candidate_pairs =
false;  

Later we'll want something in RtcConfig that's similar, perhaps
presume_connected_fully_relayed_ice.

"Fully relayed" == "TURN-TURN", except also covers future ways of doing
fully-relayed which may not even involve TURN.

[Taylor Brandstetter, 2016/06/16 00:13:41]

I don't like just "presume connected" because it doesn't tell us *why* they
should be presumed connected. The actual piece of information being provided is
that CreatePermission is not needed for fully relayed connections. So I think
that's what the variable should be called; nothing more, nothing less. Unless
there are other reasons why a fully-relayed connection may be presumed
connected.

[pthatcher1, 2016/06/16 23:31:36]

But this flag doesn't just mean CreatePermission isn't needed.  It's also saying
the application is opting into sending media before an ICE check response is
received, which I think is a bigger deal.  So something about that needs to be
in the name.

+
   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 turn_to_turn_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),
+        turn_to_turn_createpermission_needed(
+            turn_to_turn_no_createpermission_needed) {}
 };
 
 bool BadTransportDescription(const std::string& desc, std::string* err_desc);