Replace more for loops in GN

tools/gn/value_extractors.cc

 // Copyright (c) 2013 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 "tools/gn/value_extractors.h"
 
 #include "tools/gn/build_settings.h"
 #include "tools/gn/err.h"
 #include "tools/gn/label.h"
 #include "tools/gn/source_dir.h"
@@ skipping 24 matching lines @@
 // there are duplicates.
 template<typename T, class Converter>
 bool ListValueUniqueExtractor(const Value& value,
                               UniqueVector<T>* dest,
                               Err* err,
                               const Converter& converter) {
   if (!value.VerifyTypeIs(Value::LIST, err))
     return false;
   const std::vector<Value>& input_list = value.list_value();
 
-  for (size_t i = 0; i < input_list.size(); i++) {
+  for (const auto& item : input_list) {
     T new_one;
-    if (!converter(input_list[i], &new_one, err))
+    if (!converter(item, &new_one, err))
       return false;
     if (!dest->push_back(new_one)) {
       // Already in the list, throw error.
-      *err = Err(input_list[i], "Duplicate item in list");
+      *err = Err(item, "Duplicate item in list");
       size_t previous_index = dest->IndexOf(new_one);
       err->AppendSubErr(Err(input_list[previous_index],
                             "This was the previous definition."));
       return false;
     }
   }
   return true;
 }
 
 // This extractor rejects files with system-absolute file paths. If we need
@@ skipping 74 matching lines @@
 
 }  // namespace
 
 bool ExtractListOfStringValues(const Value& value,
                                std::vector<std::string>* dest,
                                Err* err) {
   if (!value.VerifyTypeIs(Value::LIST, err))
     return false;
   const std::vector<Value>& input_list = value.list_value();
   dest->reserve(input_list.size());
-  for (size_t i = 0; i < input_list.size(); i++) {
-    if (!input_list[i].VerifyTypeIs(Value::STRING, err))
+  for (const auto& item : input_list) {
+    if (!item.VerifyTypeIs(Value::STRING, err))
       return false;
-    dest->push_back(input_list[i].string_value());
+    dest->push_back(item.string_value());
   }
   return true;
 }
 
 bool ExtractListOfRelativeFiles(const BuildSettings* build_settings,
                                 const Value& value,
                                 const SourceDir& current_dir,
                                 std::vector<SourceFile>* files,
                                 Err* err) {
   return ListValueExtractor(value, files, err,
@@ skipping 50 matching lines @@
 }
 
 bool ExtractRelativeFile(const BuildSettings* build_settings,
                          const Value& value,
                          const SourceDir& current_dir,
                          SourceFile* file,
                          Err* err) {
   RelativeFileConverter converter(build_settings, current_dir);
   return converter(value, file, err);
 }