Use continual gathering to restore backup connections

webrtc/p2p/base/fakeportallocator.h

Index: webrtc/p2p/base/fakeportallocator.h
diff --git a/webrtc/p2p/base/fakeportallocator.h b/webrtc/p2p/base/fakeportallocator.h
index 58e1d5fac67d2e674a37055c3d6b7949b3f0ce97..8bccf83c421b8a91cce8350fa151bde06cd24383 100644
--- a/webrtc/p2p/base/fakeportallocator.h
+++ b/webrtc/p2p/base/fakeportallocator.h
@@ -21,6 +21,7 @@
 #include "webrtc/p2p/base/udpport.h"
 
 namespace rtc {
+class Network;
 class SocketFactory;
 class Thread;
 }
@@ -147,6 +148,11 @@ class FakePortAllocatorSession : public PortAllocatorSession {
   std::vector<Candidate> ReadyCandidates() const override {
     return candidates_;
   }
+
+  std::vector<Candidate> ReadyCandidates(PortInterface* port) const override {
+    return port_->Candidates();
+  }
+
   bool CandidatesAllocationDone() const override { return allocation_done_; }
 
   int port_config_count() { return port_config_count_; }
@@ -218,6 +224,8 @@ class FakePortAllocator : public cricket::PortAllocator {
 
   void SetNetworkIgnoreMask(int network_ignore_mask) override {}
 
+  rtc::NetworkManager* network_manager() const override { return nullptr; }
+
   cricket::PortAllocatorSession* CreateSessionInternal(
       const std::string& content_name,
       int component,