Add quic_test_loopback used for tests only.

net/quic/platform/api/quic_ip_address.h

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_QUIC_PLATFORM_API_QUIC_IP_ADDRESS_H_
 #define NET_QUIC_PLATFORM_API_QUIC_IP_ADDRESS_H_
 
 #include <string>
 
 #include "net/quic/platform/api/quic_export.h"
 #include "net/quic/platform/impl/quic_ip_address_impl.h"
 
 namespace net {
 
 class QUIC_EXPORT_PRIVATE QuicIpAddress {
   // A class representing an IPv4 or IPv6 address in QUIC. The actual
   // implementation (platform dependent) of an IP address is in
   // QuicIpAddressImpl.
  public:
   enum : size_t {
     kIPv4AddressSize = QuicIpAddressImpl::kIPv4AddressSize,
     kIPv6AddressSize = QuicIpAddressImpl::kIPv6AddressSize
   };
+
+  // TODO(fayang): Remove Loopback*() and use TestLoopback*() in tests.
   static QuicIpAddress Loopback4();
   static QuicIpAddress Loopback6();
   static QuicIpAddress Any4();
   static QuicIpAddress Any6();
 
   QuicIpAddress() = default;
   QuicIpAddress(const QuicIpAddress& other) = default;
   explicit QuicIpAddress(const QuicIpAddressImpl& impl);
   QuicIpAddress& operator=(const QuicIpAddress& other) = default;
   QuicIpAddress& operator=(QuicIpAddress&& other) = default;
@@ skipping 28 matching lines @@
 
   const QuicIpAddressImpl& impl() const { return impl_; }
 
  private:
   QuicIpAddressImpl impl_;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_PLATFORM_API_QUIC_IP_ADDRESS_H_