Rewrite base::JSONReader to be 35-40% faster, depending on the input string.

chrome/browser/extensions/settings/settings_leveldb_storage.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/extensions/settings/settings_leveldb_storage.h"
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/file_util.h"
 #include "base/json/json_reader.h"
@@ skipping 146 matching lines @@
   base::JSONReader json_reader;
   leveldb::ReadOptions options = leveldb::ReadOptions();
   // All interaction with the db is done on the same thread, so snapshotting
   // isn't strictly necessary.  This is just defensive.
   scoped_ptr<DictionaryValue> settings(new DictionaryValue());
 
   ScopedSnapshot snapshot(db_.get());
   options.snapshot = snapshot.get();
   scoped_ptr<leveldb::Iterator> it(db_->NewIterator(options));
   for (it->SeekToFirst(); it->Valid(); it->Next()) {
-    Value* value =
-        json_reader.JsonToValue(it->value().ToString(), false, false);
+    Value* value = json_reader.ReadToValue(it->value().ToString());
     if (value != NULL) {
       settings->SetWithoutPathExpansion(it->key().ToString(), value);
     } else {
       // TODO(kalman): clear the offending non-JSON value from the database.
       LOG(ERROR) << "Invalid JSON: " << it->value().ToString();
     }
   }
 
   if (!it->status().ok()) {
     LOG(ERROR) << "DB iteration failed: " << it->status().ToString();
@@ skipping 90 matching lines @@
   // isn't strictly necessary.  This is just defensive.
   leveldb::WriteBatch batch;
   scoped_ptr<SettingChangeList> changes(new SettingChangeList());
 
   ScopedSnapshot snapshot(db_.get());
   read_options.snapshot = snapshot.get();
   scoped_ptr<leveldb::Iterator> it(db_->NewIterator(read_options));
   for (it->SeekToFirst(); it->Valid(); it->Next()) {
     const std::string key = it->key().ToString();
     const std::string old_value_json = it->value().ToString();
-    Value* old_value =
-        base::JSONReader().JsonToValue(old_value_json, false, false);
+    Value* old_value = base::JSONReader().ReadToValue(old_value_json);
     if (old_value) {
       changes->push_back(SettingChange(key, old_value, NULL));
     } else {
       LOG(ERROR) << "Invalid JSON in database: " << old_value_json;
     }
     batch.Delete(key);
   }
 
   if (!it->status().ok()) {
     LOG(WARNING) << "Clear iteration failed: " << it->status().ToString();
@@ skipping 21 matching lines @@
   if (s.IsNotFound()) {
     // Despite there being no value, it was still a success.
     return true;
   }
 
   if (!s.ok()) {
     LOG(ERROR) << "Error reading from database: " << s.ToString();
     return false;
   }
 
-  Value* value = base::JSONReader().JsonToValue(value_as_json, false, false);
+  Value* value = base::JSONReader().ReadToValue(value_as_json);
   if (value == NULL) {
     // TODO(kalman): clear the offending non-JSON value from the database.
     LOG(ERROR) << "Invalid JSON in database: " << value_as_json;
     return false;
   }
 
   setting->reset(value);
   return true;
 }
 
 bool SettingsLeveldbStorage::IsEmpty() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   scoped_ptr<leveldb::Iterator> it(db_->NewIterator(leveldb::ReadOptions()));
 
   it->SeekToFirst();
   bool is_empty = !it->Valid();
   if (!it->status().ok()) {
     LOG(ERROR) << "Checking DB emptiness failed: " << it->status().ToString();
     return false;
   }
   return is_empty;
 }
 
 }  // namespace extensions