Generate param traits size methods for IPC files in content/ (and traits it depends on).

url/ipc/url_param_traits.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 URL_IPC_URL_PARAM_TRAITS_H_
 #define URL_IPC_URL_PARAM_TRAITS_H_
 
 #include "ipc/ipc_message_utils.h"
 #include "url/gurl.h"
 #include "url/ipc/url_ipc_export.h"
 
 namespace IPC {
 
 template <>
 struct URL_IPC_EXPORT ParamTraits<GURL> {
   typedef GURL param_type;
+  static void GetSize(base::PickleSizer* s, const param_type& p);
   static void Write(base::Pickle* m, const param_type& p);
   static bool Read(const base::Pickle* m,
                    base::PickleIterator* iter,
                    param_type* p);
   static void Log(const param_type& p, std::string* l);
 };
 
 }  // namespace IPC
 
 #endif  // URL_IPC_URL_PARAM_TRAITS_H_