Add SocketFactoryInterface::Prepare and fix how symmetric NAT is determined.

Also remove Bind from ServerSocket interface as it's not needed anymore.

BUG=4576
R=pthatcher@webrtc.org

Review URL: https://codereview.webrtc.org/1162263012

Cr-Commit-Position: refs/heads/master@{#9371}

webrtc/p2p/stunprober/stunprober.cc

@@ -74,28 +74,11 @@ void StunProber::Requester::SendStunRequest() {
   auto addr = server_ips_[num_request_sent_];
   request.server_addr = addr.ipaddr();
 
-  int rv = 0;
-
-  // Only bind to the interface at the first request.
-  if (num_request_sent_ == 0) {
-    rtc::IPAddress local_addr;
-    rv = prober_->GetLocalAddress(&local_addr);
-    if (rv != 0) {
-      prober_->End(GENERIC_FAILURE, rv);
-      return;
-    }
-    rv = socket_->Bind(rtc::SocketAddress(local_addr, 0));
-    if (rv < 0) {
-      prober_->End(GENERIC_FAILURE, rv);
-      return;
-    }
-  }
-
   // The write must succeed immediately. Otherwise, the calculating of the STUN
   // request timing could become too complicated. Callback is ignored by passing
   // empty AsyncCallback.
-  rv = socket_->SendTo(addr, const_cast<char*>(request_packet->Data()),
-                       request_packet->Length(), AsyncCallback());
+  int rv = socket_->SendTo(addr, const_cast<char*>(request_packet->Data()),
+                           request_packet->Length(), AsyncCallback());
   if (rv < 0) {
     prober_->End(WRITE_FAILED, rv);
     return;
@@ -279,7 +262,12 @@ void StunProber::OnServerResolved(int index, int result) {
     return;
   }
 
-  MaybeScheduleStunRequests();
+  socket_factory_->Prepare(GetTotalClientSockets(), GetTotalServerSockets(),
+                           [this](int result) {
+                             if (result == 0) {
+                               this->MaybeScheduleStunRequests();
+                             }
+                           });
 }
 
 int StunProber::GetLocalAddress(rtc::IPAddress* addr) {
@@ -440,6 +428,8 @@ bool StunProber::GetStats(StunProber::Stats* prob_stats) {
   stats.num_request_sent = num_sent;
   stats.num_response_received = num_received;
   stats.target_request_interval_ns = interval_ms_ * 1000;
+  stats.symmetric_nat =
+      stats.srflx_addrs.size() > static_cast<size_t>(GetTotalServerSockets());
 
   if (num_sent) {
     stats.success_percent = static_cast<int>(100 * num_received / num_sent);

webrtc/p2p/stunprober/stunprober.h

@@ -55,7 +55,6 @@ class SocketInterface {
     FAILED = -2,
   };
   SocketInterface() {}
-  virtual int GetLocalAddress(rtc::SocketAddress* local_address) = 0;
   virtual void Close() = 0;
   virtual ~SocketInterface() {}
 
@@ -70,6 +69,8 @@ class ClientSocketInterface : public SocketInterface {
   // getsockname will only return 0.0.0.0.
   virtual int Connect(const rtc::SocketAddress& addr) = 0;
 
+  virtual int GetLocalAddress(rtc::SocketAddress* local_address) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ClientSocketInterface);
 };
@@ -77,7 +78,6 @@ class ClientSocketInterface : public SocketInterface {
 class ServerSocketInterface : public SocketInterface {
  public:
   ServerSocketInterface() {}
-  virtual int Bind(const rtc::SocketAddress& addr) = 0;
 
   virtual int SendTo(const rtc::SocketAddress& addr,
                      char* buf,
@@ -99,6 +99,14 @@ class ServerSocketInterface : public SocketInterface {
 class SocketFactoryInterface {
  public:
   SocketFactoryInterface() {}
+  // To provide a chance to prepare the sockets that we need. This is
+  // implemented for chrome renderer process as the socket needs to be ready to
+  // use in browser process.
+  virtual void Prepare(size_t total_client_socket,
+                       size_t total_server_socket,
+                       AsyncCallback callback) {
+    callback(0);
+  }
   virtual ClientSocketInterface* CreateClientSocket() = 0;
   virtual ServerSocketInterface* CreateServerSocket(
       size_t send_buffer_size,
@@ -134,6 +142,7 @@ class StunProber {
     int num_request_sent = 0;
     int num_response_received = 0;
     bool behind_nat = false;
+    bool symmetric_nat = false;
     int average_rtt_ms = -1;
     int success_percent = 0;
     int target_request_interval_ns = 0;
@@ -148,8 +157,6 @@ class StunProber {
 
     // If the srflx_addrs has more than 1 element, the NAT is symmetric.
     std::set<std::string> srflx_addrs;
-
-    bool symmetric_nat() { return srflx_addrs.size() > 1; }
   };
 
   // StunProber is not thread safe. It's task_runner's responsibility to ensure
@@ -265,6 +272,12 @@ class StunProber {
     return num_request_sent_ >= requests_per_ip_ * all_servers_ips_.size();
   }
 
+  int GetTotalClientSockets() { return 1; }
+  int GetTotalServerSockets() {
+    return (shared_socket_mode_ ? 1 : all_servers_ips_.size()) *
+           requests_per_ip_;
+  }
+
   bool SendNextRequest();
 
   // Will be invoked in 1ms intervals and schedule the next request from the

webrtc/p2p/stunprober/stunprober_dependencies.h

@@ -35,10 +35,6 @@ class Socket : public ClientSocketInterface,
     return MapResult(socket_->Connect(addr));
   }
 
-  int Bind(const rtc::SocketAddress& addr) override {
-    return MapResult(socket_->Bind(addr));
-  }
-
   int SendTo(const rtc::SocketAddress& addr,
              char* buf,
              size_t buf_len,