tools/gn: Convert for loops to use the new range-based loops in C++11.

tools/gn/substitution_pattern.cc

 // Copyright 2014 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/substitution_pattern.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/err.h"
 #include "tools/gn/filesystem_utils.h"
@@ skipping 83 matching lines @@
 // static
 SubstitutionPattern SubstitutionPattern::MakeForTest(const char* str) {
   Err err;
   SubstitutionPattern pattern;
   CHECK(pattern.Parse(str, nullptr, &err)) << err.message();
   return pattern;
 }
 
 std::string SubstitutionPattern::AsString() const {
   std::string result;
-  for (size_t i = 0; i < ranges_.size(); i++) {
-    if (ranges_[i].type == SUBSTITUTION_LITERAL)
-      result.append(ranges_[i].literal);
+  for (const auto& elem : ranges_) {
+    if (elem.type == SUBSTITUTION_LITERAL)
+      result.append(elem.literal);
     else
-      result.append(kSubstitutionNames[ranges_[i].type]);
+      result.append(kSubstitutionNames[elem.type]);
   }
   return result;
 }
 
 void SubstitutionPattern::FillRequiredTypes(SubstitutionBits* bits) const {
-  for (size_t i = 0; i < ranges_.size(); i++) {
-    if (ranges_[i].type != SUBSTITUTION_LITERAL)
-      bits->used[static_cast<size_t>(ranges_[i].type)] = true;
+  for (const auto& elem : ranges_) {
+    if (elem.type != SUBSTITUTION_LITERAL)
+      bits->used[static_cast<size_t>(elem.type)] = true;
   }
 }
 
 bool SubstitutionPattern::IsInOutputDir(const BuildSettings* build_settings,
                                         Err* err) const {
   if (ranges_.empty()) {
     *err = Err(origin_, "This is empty but I was expecting an output file.");
     return false;
   }
 
@@ skipping 11 matching lines @@
           "File is not inside output directory.",
           "The given file should be in the output directory. Normally you\n"
           "would specify\n\"$target_out_dir/foo\" or "
           "\"{{source_gen_dir}}/foo\".");
       return false;
     }
   }
 
   return true;
 }