Move UseNonBlockingIO from a windows-only method

net/udp/udp_client_socket.h

Index: net/udp/udp_client_socket.h
diff --git a/net/udp/udp_client_socket.h b/net/udp/udp_client_socket.h
index ca563bbc0f1f45e3e04c8be0d33257e8f6748b08..c460d28c01e99f03e2c61a91c140ea9439d0fbac 100644
--- a/net/udp/udp_client_socket.h
+++ b/net/udp/udp_client_socket.h
@@ -41,16 +41,13 @@ class NET_EXPORT_PRIVATE UDPClientSocket : public DatagramClientSocket {
   void Close() override;
   int GetPeerAddress(IPEndPoint* address) const override;
   int GetLocalAddress(IPEndPoint* address) const override;
+  void UseNonBlockingIO() override;
   int SetReceiveBufferSize(int32_t size) override;
   int SetSendBufferSize(int32_t size) override;
   const BoundNetLog& NetLog() const override;
 
-#if defined(OS_WIN)
   // Switch to use non-blocking IO. Must be called right after construction and
   // before other calls.
-  void UseNonBlockingIO();
-#endif
-
  private:
   UDPSocket socket_;
   NetworkChangeNotifier::NetworkHandle network_;