Refactor Pickle Read methods to use higher performance PickleIterator.

chrome/browser/sessions/session_service.cc

 // 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.
 
 #include "chrome/browser/sessions/session_service.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 #include <vector>
@@ skipping 1245 matching lines @@
   }
   StartSaveTimer();
 }
 
 bool SessionService::ReplacePendingCommand(SessionCommand* command) {
   // We only optimize page navigations, which can happen quite frequently and
   // are expensive. If necessary, other commands could be searched for as
   // well.
   if (command->id() != kCommandUpdateTabNavigation)
     return false;
-  void* iterator = NULL;
   scoped_ptr<Pickle> command_pickle(command->PayloadAsPickle());
+  PickleReader iterator(*command_pickle);
   SessionID::id_type command_tab_id;
   int command_nav_index;
   if (!command_pickle->ReadInt(&iterator, &command_tab_id) ||
       !command_pickle->ReadInt(&iterator, &command_nav_index)) {
     return false;
   }
   for (std::vector<SessionCommand*>::reverse_iterator i =
        pending_commands().rbegin(); i != pending_commands().rend(); ++i) {
     SessionCommand* existing_command = *i;
     if (existing_command->id() == kCommandUpdateTabNavigation) {
       SessionID::id_type existing_tab_id;
       int existing_nav_index;
       {
         // Creating a pickle like this means the Pickle references the data from
         // the command. Make sure we delete the pickle before the command, else
         // the pickle references deleted memory.
         scoped_ptr<Pickle> existing_pickle(existing_command->PayloadAsPickle());
-        iterator = NULL;
+        iterator = PickleReader(*existing_pickle);
         if (!existing_pickle->ReadInt(&iterator, &existing_tab_id) ||
             !existing_pickle->ReadInt(&iterator, &existing_nav_index)) {
           return false;
         }
       }
       if (existing_tab_id == command_tab_id &&
           existing_nav_index == command_nav_index) {
         // existing_command is an update for the same tab/index pair. Replace
         // it with the new one. We need to add to the end of the list just in
         // case there is a prune command after the update command.
@@ skipping 236 matching lines @@
       50);
   if (use_long_period) {
     std::string long_name_("SessionRestore.SaveLongPeriod");
     UMA_HISTOGRAM_CUSTOM_TIMES(long_name_,
         delta,
         save_delay_in_mins_,
         save_delay_in_hrs_,
         50);
   }
 }