IWYU fixes for url/...

url/url_canon_ip.h

 // Copyright 2013 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 URL_URL_CANON_IP_H_
 #define URL_URL_CANON_IP_H_
 
 #include "base/strings/string16.h"
 #include "url/third_party/mozilla/url_parse.h"
 #include "url/url_canon.h"
 #include "url/url_export.h"
 
 namespace url {
 
+struct Component;
+
 // Writes the given IPv4 address to |output|.
 URL_EXPORT void AppendIPv4Address(const unsigned char address[4],
                                   CanonOutput* output);
 
 // Writes the given IPv6 address to |output|.
 URL_EXPORT void AppendIPv6Address(const unsigned char address[16],
                                   CanonOutput* output);
 
 // Searches the host name for the portions of the IPv4 address. On success,
 // each component will be placed into |components| and it will return true.
@@ skipping 48 matching lines @@
 URL_EXPORT bool IPv6AddressToNumber(const char* spec,
                                     const Component& host,
                                     unsigned char address[16]);
 URL_EXPORT bool IPv6AddressToNumber(const base::char16* spec,
                                     const Component& host,
                                     unsigned char address[16]);
 
 }  // namespace url
 
 #endif  // URL_URL_CANON_IP_H_