Refactor StringPiece hash.

net/quic/quic_blocked_writer_interface.h

 // Copyright (c) 2012 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.
 
 // This is an interface for all objects that want to be notified that
 // the underlying UDP socket is available for writing (not write blocked
 // anymore).
 
 #ifndef NET_QUIC_QUIC_BLOCKED_WRITER_INTERFACE_H_
 #define NET_QUIC_QUIC_BLOCKED_WRITER_INTERFACE_H_
 
 #include <stddef.h>
 
 #include "net/base/net_export.h"
 
 namespace net {
 
 class NET_EXPORT_PRIVATE QuicBlockedWriterInterface {
  public:
   virtual ~QuicBlockedWriterInterface() {}
 
   // Called by the PacketWriter when the underlying socket becomes writable
   // so that the BlockedWriter can go ahead and try writing.
   virtual void OnCanWrite() = 0;
 };
 
-}  // namespace net
-
-#if defined(COMPILER_GCC)
-namespace BASE_HASH_NAMESPACE {
 // Hash pointers as if they were int's, but bring more entropy to the lower
 // bits.
-template <>
-struct hash<net::QuicBlockedWriterInterface*> {
+struct QuicBlockedWriterInterfacePtrHash {
   std::size_t operator()(const net::QuicBlockedWriterInterface* ptr) const {
     size_t k = reinterpret_cast<size_t>(ptr);
     return k + (k >> 6);
   }
 };
-}
-#endif
+
+}  // namespace net
 
 #endif  // NET_QUIC_QUIC_BLOCKED_WRITER_INTERFACE_H_