IPC pickling optimization for render passes.

content/common/cc_messages.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.
 //
 // IPC Messages sent between compositor instances.
 
 #include "cc/output/begin_frame_args.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
 #include "cc/output/filter_operation.h"
@@ skipping 59 matching lines @@
   typedef gfx::Transform param_type;
   static void Write(Message* m, const param_type& p);
   static bool Read(const Message* m, PickleIterator* iter, param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template <>
 struct CONTENT_EXPORT ParamTraits<cc::RenderPass> {
   typedef cc::RenderPass param_type;
   static void Write(Message* m, const param_type& p);
+  static size_t ReserveSizeForWrite(const param_type& p);

[Tom Sepez, 2013/10/24 17:48:06]

I'm not sure making this a method of this particular specialization of the
templated paramtraits class is the right thing to do since none of the other
specializations will implement this. It doesn't need to be called oustide of the
write() method, so I'd suggest using a static  function or a function in an
anonymous namespace in the .cc file.

[danakj, 2013/10/24 17:51:38]

Alright. I wanted to keep it close to the Write() method so that people would
more obviously see to update both together..

   static bool Read(const Message* m, PickleIterator* iter, param_type* r);
   static void Log(const param_type& p, std::string* l);
 };
 
 template<>
 struct CONTENT_EXPORT ParamTraits<cc::CompositorFrame> {
   typedef cc::CompositorFrame param_type;
   static void Write(Message* m, const param_type& p);
   static bool Read(const Message* m, PickleIterator* iter, param_type* p);
   static void Log(const param_type& p, std::string* l);
@@ skipping 167 matching lines @@
   IPC_STRUCT_TRAITS_MEMBER(size)
   IPC_STRUCT_TRAITS_MEMBER(sub_buffer_rect)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(cc::SoftwareFrameData)
   IPC_STRUCT_TRAITS_MEMBER(id)
   IPC_STRUCT_TRAITS_MEMBER(size)
   IPC_STRUCT_TRAITS_MEMBER(damage_rect)
   IPC_STRUCT_TRAITS_MEMBER(handle)
 IPC_STRUCT_TRAITS_END()