WebRTC should generate default private address even when adapter enumeration is disabled.

webrtc/base/network.h

Index: webrtc/base/network.h
diff --git a/webrtc/base/network.h b/webrtc/base/network.h
index ab3a88dc7dc0c4dd511d5da7aee4b7c035975657..3cdc1253a1fd464d4b020f502a9b58dd43a48c93 100644
--- a/webrtc/base/network.h
+++ b/webrtc/base/network.h
@@ -28,6 +28,9 @@ struct ifaddrs;
 
 namespace rtc {
 
+extern const char kPublicIPv4Host[];
+extern const char kPublicIPv6Host[];
+
 class Network;
 class NetworkMonitorInterface;
 class Thread;
@@ -51,9 +54,17 @@ const int kDefaultNetworkIgnoreMask = ADAPTER_TYPE_LOOPBACK;
 std::string MakeNetworkKey(const std::string& name, const IPAddress& prefix,
                            int prefix_length);
 
+class DefaultLocalAddressProvider {
+ public:
+  virtual ~DefaultLocalAddressProvider() = default;
+  // Default local address is the interface used to route to public internet on
+  // a multi-homed endpoint.
+  virtual bool GetDefaultLocalAddress(int family, IPAddress* ipaddr) const = 0;
+};
+
 // Generic network manager interface. It provides list of local
 // networks.
-class NetworkManager {
+class NetworkManager : public DefaultLocalAddressProvider {
  public:
   typedef std::vector<Network*> NetworkList;
 
@@ -67,7 +78,7 @@ class NetworkManager {
   };
 
   NetworkManager();
-  virtual ~NetworkManager();
+  ~NetworkManager() override;
 
   // Called when network list is updated.
   sigslot::signal0<> SignalNetworksChanged;
@@ -99,6 +110,8 @@ class NetworkManager {
   // TODO(guoweis): remove this body when chromium implements this.
   virtual void GetAnyAddressNetworks(NetworkList* networks) {}
 
+  bool GetDefaultLocalAddress(int family, IPAddress* ipaddr) const override;
+
   // Dumps a list of networks available to LS_INFO.
   virtual void DumpNetworks(bool include_ignored) {}
 
@@ -128,6 +141,8 @@ class NetworkManagerBase : public NetworkManager {
 
   EnumerationPermission enumeration_permission() const override;
 
+  bool GetDefaultLocalAddress(int family, IPAddress* ipaddr) const override;
+
  protected:
   typedef std::map<std::string, Network*> NetworkMap;
   // Updates |networks_| with the networks listed in |list|. If
@@ -146,6 +161,9 @@ class NetworkManagerBase : public NetworkManager {
     enumeration_permission_ = state;
   }
 
+  void set_default_local_addresses(const IPAddress& ipv4,
+                                   const IPAddress& ipv6);
+
  private:
   friend class NetworkTest;
 
@@ -159,6 +177,9 @@ class NetworkManagerBase : public NetworkManager {
 
   rtc::scoped_ptr<rtc::Network> ipv4_any_address_network_;
   rtc::scoped_ptr<rtc::Network> ipv6_any_address_network_;
+
+  IPAddress default_local_ipv4_address_;
+  IPAddress default_local_ipv6_address_;
 };
 
 // Basic implementation of the NetworkManager interface that gets list
@@ -220,6 +241,11 @@ class BasicNetworkManager : public NetworkManagerBase,
   // based on the network's property instead of any individual IP.
   bool IsIgnoredNetwork(const Network& network) const;
 
+  // This function connects a UDP socket to a public address and returns the
+  // local address associated it. Since it binds to the "any" address
+  // internally, it returns the default local address on a multi-homed endpoint.
+  IPAddress QueryDefaultLocalAddress(int family) const;
+
  private:
   friend class NetworkTest;
 
@@ -247,13 +273,26 @@ class BasicNetworkManager : public NetworkManagerBase,
 // Represents a Unix-type network interface, with a name and single address.
 class Network {
  public:
-  Network(const std::string& name, const std::string& description,
-          const IPAddress& prefix, int prefix_length);
-
-  Network(const std::string& name, const std::string& description,
-          const IPAddress& prefix, int prefix_length, AdapterType type);
+  Network(const std::string& name,
+          const std::string& description,
+          const IPAddress& prefix,
+          int prefix_length);
+
+  Network(const std::string& name,
+          const std::string& description,
+          const IPAddress& prefix,
+          int prefix_length,
+          AdapterType type);
   ~Network();
 
+  const DefaultLocalAddressProvider* default_local_address_provider() {
+    return default_local_address_provider_;
+  }
+  void set_default_local_address_provider(
+      const DefaultLocalAddressProvider* provider) {
+    default_local_address_provider_ = provider;
+  }
+
   // Returns the name of the interface this network is associated wtih.
   const std::string& name() const { return name_; }
 
@@ -323,6 +362,7 @@ class Network {
   std::string ToString() const;
 
  private:
+  const DefaultLocalAddressProvider* default_local_address_provider_ = nullptr;
   std::string name_;
   std::string description_;
   IPAddress prefix_;