Bundle DidOverscrollParams with the InputEventAck

ipc/ipc_message_utils.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.
 
 #ifndef IPC_IPC_MESSAGE_UTILS_H_
 #define IPC_IPC_MESSAGE_UTILS_H_
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/containers/small_map.h"
 #include "base/files/file.h"
 #include "base/format_macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/tuple.h"
 #include "ipc/ipc_message_start.h"
 #include "ipc/ipc_param_traits.h"
 #include "ipc/ipc_sync_message.h"
 
 #if defined(COMPILER_GCC)
@@ skipping 672 matching lines @@
       if (!ReadParam(m, iter, &value))
         return false;
     }
     return true;
   }
   static void Log(const param_type& p, std::string* l) {
     l->append("<base::SmallMap>");
   }
 };
 
+template <class P>
+struct ParamTraits<scoped_ptr<P> > {
+  typedef scoped_ptr<P> param_type;
+  static void Write(Message* m, const param_type& p) {
+    bool valid = !!p;
+    WriteParam(m, valid);
+    if (valid)
+      WriteParam(m, *p);
+  }
+  static bool Read(const Message* m, PickleIterator* iter, param_type* r) {
+    bool valid = false;
+    if (!ReadParam(m, iter, &valid))
+      return false;
+
+    if (!valid) {
+      r->reset();
+      return true;
+    }
+
+    param_type temp(new P());
+    if (!ReadParam(m, iter, temp.get()))
+      return false;
+
+    r->swap(temp);
+    return true;
+  }
+  static void Log(const param_type& p, std::string* l) {
+    if (p)
+      LogParam(*p, l);
+    else
+      l->append("NULL");
+  }
+};
+
 // IPC types ParamTraits -------------------------------------------------------
 
 // A ChannelHandle is basically a platform-inspecific wrapper around the
 // fact that IPC endpoints are handled specially on POSIX.  See above comments
 // on FileDescriptor for more background.
 template<>
 struct IPC_EXPORT ParamTraits<IPC::ChannelHandle> {
   typedef ChannelHandle param_type;
   static void Write(Message* m, const param_type& p);
   static bool Read(const Message* m, PickleIterator* iter, param_type* r);
@@ skipping 195 matching lines @@
   template<typename TA, typename TB, typename TC, typename TD, typename TE>
   static void WriteReplyParams(Message* reply, TA a, TB b, TC c, TD d, TE e) {
     ReplyParam p(a, b, c, d, e);
     WriteParam(reply, p);
   }
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_MESSAGE_UTILS_H_