Replace more for loops in GN

tools/gn/binary_target_generator.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/binary_target_generator.h"
 
 #include "tools/gn/config_values_generator.h"
 #include "tools/gn/deps_iterator.h"
 #include "tools/gn/err.h"
 #include "tools/gn/functions.h"
@@ skipping 100 matching lines @@
   if (!value)
     return true;
 
   UniqueVector<Label> circular;
   ExtractListOfUniqueLabels(*value, scope_->GetSourceDir(),
                             ToolchainLabelForScope(scope_), &circular, err_);
   if (err_->has_error())
     return false;
 
   // Validate that all circular includes entries are in the deps.
-  for (size_t circular_i = 0; circular_i < circular.size(); circular_i++) {
+  for (const auto& cur : circular) {
     bool found_dep = false;
     for (const auto& dep_pair : target_->GetDeps(Target::DEPS_LINKED)) {
-      if (dep_pair.label == circular[circular_i]) {
+      if (dep_pair.label == cur) {
         found_dep = true;
         break;
       }
     }
     if (!found_dep) {
       *err_ = Err(*value, "Label not in deps.",
-          "The label \"" + circular[circular_i].GetUserVisibleName(false) +
+          "The label \"" + cur.GetUserVisibleName(false) +
           "\"\nwas not in the deps of this target. "
           "allow_circular_includes_from only allows\ntargets present in the "
           "deps.");
       return false;
     }
   }
 
   // Add to the set.
-  for (size_t i = 0; i < circular.size(); i++)
-    target_->allow_circular_includes_from().insert(circular[i]);
+  for (const auto& cur : circular)
+    target_->allow_circular_includes_from().insert(cur);
   return true;
 }