Use continual gathering to restore backup connections

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..b582070ca45cbc484a68dff6566ddc45e3214b7d 100644
--- a/webrtc/p2p/base/transport.h
+++ b/webrtc/p2p/base/transport.h
@@ -81,6 +81,16 @@ enum IceGatheringState {
   kIceGatheringComplete,
 };
 
+enum ContinualGatheringPolicy {
+  // All port allocator sessions will stop after a writable connection is found.
+  GATHER_ONCE = 0;
+  // The most recent port allocator session will keep on running.
+  GATHER_CONTINUALLY;
+  // The most recent port allocator session will keep on running, and it will
+  // try to recover connectivity if the channel becomes not connected.
+  GATHER_CONTINUALLY_AND_RECOVER;
+};
+
 // Stats that we can return about the connections for a transport channel.
 // TODO(hta): Rename to ConnectionStats
 struct ConnectionInfo {
@@ -158,8 +168,13 @@ struct IceConfig {
   // Time interval in milliseconds to ping a backup connection when the ICE
   // channel is strongly connected.
   int backup_connection_ping_interval = -1;
-  // If true, the most recent port allocator session will keep on running.
-  bool gather_continually = false;
+
+  ContinualGatheringPolicy gathering_policy = GATHER_ONCE;
+
+  bool gather_continually() {
+    return gathering_policy == GATHER_CONTINUALLY ||
+           gathering_policy == GATHER_CONTINUALLY_AND_RECOVER;
+  }
 
   // Whether we should prioritize Relay/Relay candidate when nothing
   // is writable yet.
@@ -170,18 +185,25 @@ struct IceConfig {
   // (Default value is a little less than 2 * STRONG_PING_INTERVAL).
   int max_strong_interval = -1;
 
+  // Interval to check on all networks and to perform ICE regathering on any
+  // active network having no connection on it.
+  int regather_on_failed_networks_interval = -1;
+
   IceConfig() {}
   IceConfig(int receiving_timeout_ms,
             int backup_connection_ping_interval,
-            bool gather_continually,
+            bool gathering_policy,
             bool prioritize_most_likely_candidate_pairs,
-            int max_strong_interval_ms)
+            int max_strong_interval_ms,
+            int regather_on_failed_networks_interval_ms)
       : receiving_timeout(receiving_timeout_ms),
         backup_connection_ping_interval(backup_connection_ping_interval),
-        gather_continually(gather_continually),
+        gathering_policy(gathering_policy),
         prioritize_most_likely_candidate_pairs(
             prioritize_most_likely_candidate_pairs),
-        max_strong_interval(max_strong_interval_ms) {}
+        max_strong_interval(max_strong_interval_ms),
+        regather_on_failed_networks_interval(
+            regather_on_failed_networks_interval_ms) {}
 };
 
 bool BadTransportDescription(const std::string& desc, std::string* err_desc);