Reduce header dependencies in net/

net/base/socket.h

 // Copyright (c) 2006-2008 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_BASE_SOCKET_H_
 #define NET_BASE_SOCKET_H_
 
 #include "net/base/completion_callback.h"
-#include "net/base/io_buffer.h"
 
 namespace net {
 
+class IOBuffer;
+
 // Represents a read/write socket.
 class Socket {
  public:
   virtual ~Socket() {}
 
   // Reads data, up to buf_len bytes, from the socket.  The number of bytes
   // read is returned, or an error is returned upon failure.  Zero is returned
   // to indicate end-of-file.  ERR_IO_PENDING is returned if the operation
   // could not be completed synchronously, in which case the result will be
   // passed to the callback when available. If the operation is not completed
@@ skipping 11 matching lines @@
   // the callback is invoked or the socket is destroyed.
   // Implementations of this method should not modify the contents of the actual
   // buffer that is written to the socket.
   virtual int Write(IOBuffer* buf, int buf_len,
                     CompletionCallback* callback) = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_SOCKET_H_