Bind a socket to a network if the network handle is set.

webrtc/base/asyncsocket.h

Index: webrtc/base/asyncsocket.h
diff --git a/webrtc/base/asyncsocket.h b/webrtc/base/asyncsocket.h
index 7a859be962b56ae656dcd768f009777665c6913e..b50b554176239d0b139a87bf136823bf7e0c38d7 100644
--- a/webrtc/base/asyncsocket.h
+++ b/webrtc/base/asyncsocket.h
@@ -27,6 +27,8 @@ class AsyncSocket : public Socket {
 
   AsyncSocket* Accept(SocketAddress* paddr) override = 0;
 
+  virtual int BindToNetwork(NetworkHandle handle) = 0;

[pthatcher1, 2016/01/06 21:58:46]

Can you put a comment explaining when this should be called and what effect it
will have (Android needs it to specify the network it will be bound to).

Actually, now I think about it, I think we could avoid needing this at all.  See
my later comment for how.

[honghaiz3, 2016/01/12 20:36:41]

Acknowledged.

+
   // SignalReadEvent and SignalWriteEvent use multi_threaded_local to allow
   // access concurrently from different thread.
   // For example SignalReadEvent::connect will be called in AsyncUDPSocket ctor
@@ -60,6 +62,7 @@ class AsyncSocketAdapter : public AsyncSocket, public sigslot::has_slots<> {
   int RecvFrom(void* pv, size_t cb, SocketAddress* paddr) override;
   int Listen(int backlog) override;
   AsyncSocket* Accept(SocketAddress* paddr) override;
+  int BindToNetwork(NetworkHandle handle) override;
   int Close() override;
   int GetError() const override;
   void SetError(int error) override;