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

tools/gn/ninja_writer.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/ninja_writer.h"
 
 #include "tools/gn/builder.h"
 #include "tools/gn/loader.h"
 #include "tools/gn/location.h"
 #include "tools/gn/ninja_build_writer.h"
@@ skipping 34 matching lines @@
 }
 
 bool NinjaWriter::WriteToolchains(std::vector<const Settings*>* all_settings,
                                   std::vector<const Target*>* default_targets,
                                   Err* err) {
   // Categorize all targets by toolchain.
   typedef std::map<Label, std::vector<const Target*> > CategorizedMap;
   CategorizedMap categorized;
 
   std::vector<const BuilderRecord*> all_records = builder_->GetAllRecords();
-  for (size_t i = 0; i < all_records.size(); i++) {
-    if (all_records[i]->type() == BuilderRecord::ITEM_TARGET &&
-        all_records[i]->should_generate()) {
-      categorized[all_records[i]->label().GetToolchainLabel()].push_back(
-          all_records[i]->item()->AsTarget());
+  for (const auto& all_record : all_records) {
+    if (all_record->type() == BuilderRecord::ITEM_TARGET &&
+        all_record->should_generate()) {
+      categorized[all_record->label().GetToolchainLabel()].push_back(
+          all_record->item()->AsTarget());
       }
   }
   if (categorized.empty()) {
     Err(Location(), "No targets.",
         "I could not find any targets to write, so I'm doing nothing.")
         .PrintToStdout();
     return false;
   }
 
   Label default_label = builder_->loader()->GetDefaultToolchain();
@@ skipping 27 matching lines @@
   // should always be at least one settings object in the build.
   CHECK(!all_settings.empty());
   const Toolchain* default_toolchain =
       builder_->GetToolchain(all_settings[0]->default_toolchain_label());
 
   // Write the root buildfile.
   return NinjaBuildWriter::RunAndWriteFile(build_settings_, all_settings,
                                            default_toolchain, default_targets,
                                            err);
 }