Refactor Pickle Read methods to use higher performance PickleIterator.

ipc/ipc_message_utils_impl.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 //
 // This file contains templates forward declared (but not defined) in
 // ipc_message_utils.h so that they are only instantiated in certain files,
 // notably a few IPC unit tests.
 
 #ifndef IPC_IPC_MESSAGE_UTILS_IMPL_H_
 #define IPC_IPC_MESSAGE_UTILS_IMPL_H_
 
 namespace IPC {
 
 template <class ParamType>
 void MessageSchema<ParamType>::Write(Message* msg, const RefParam& p) {
   WriteParam(msg, p);
 }
 
 template <class ParamType>
 bool MessageSchema<ParamType>::Read(const Message* msg, Param* p) {
-  void* iter = NULL;
+  PickleIterator iter(*msg);
   if (ReadParam(msg, &iter, p))
     return true;
   NOTREACHED() << "Error deserializing message " << msg->type();
   return false;
 }
 
 template <class SendParamType, class ReplyParamType>
 void SyncMessageSchema<SendParamType, ReplyParamType>::Write(
     Message* msg,
     const RefSendParam& send) {
   WriteParam(msg, send);
 }
 
 template <class SendParamType, class ReplyParamType>
 bool SyncMessageSchema<SendParamType, ReplyParamType>::ReadSendParam(
     const Message* msg, SendParam* p) {
-  void* iter = SyncMessage::GetDataIterator(msg);
+  PickleIterator iter = SyncMessage::GetDataIterator(msg);
   return ReadParam(msg, &iter, p);
 }
 
 template <class SendParamType, class ReplyParamType>
 bool SyncMessageSchema<SendParamType, ReplyParamType>::ReadReplyParam(
     const Message* msg, typename TupleTypes<ReplyParam>::ValueTuple* p) {
-  void* iter = SyncMessage::GetDataIterator(msg);
+  PickleIterator iter = SyncMessage::GetDataIterator(msg);
   return ReadParam(msg, &iter, p);
 }
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_MESSAGE_UTILS_IMPL_H_