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

ipc/mach_port_mac.h

 // Copyright 2015 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 IPC_MACH_PORT_MAC_H_
 #define IPC_MACH_PORT_MAC_H_
 
 #include <mach/mach.h>
 
 #include "base/macros.h"
@@ skipping 53 matching lines @@
   // semantics discussed above, this MachPortAttachmentMac does not take
   // ownership of the Mach port, and assumes that the client code which receives
   // the callback will take ownership of the Mach port.
   mach_port_t mach_port_;
   DISALLOW_COPY_AND_ASSIGN(MachPortMac);
 };
 
 template <>
 struct IPC_EXPORT ParamTraits<MachPortMac> {
   typedef MachPortMac 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  // IPC_MACH_PORT_MAC_H_