Replace more for loops in GN

tools/gn/loader_unittest.cc

Index: tools/gn/loader_unittest.cc
diff --git a/tools/gn/loader_unittest.cc b/tools/gn/loader_unittest.cc
index e5a3d86009bedead648ac39cc1a42e993c835939..fc4fa5699c2c191fad849dd6e3bae70b3c42c26a 100644
--- a/tools/gn/loader_unittest.cc
+++ b/tools/gn/loader_unittest.cc
@@ -100,13 +100,12 @@ bool MockInputFileManager::HasTwoPending(const SourceFile& f1,
 void MockInputFileManager::IssueAllPending() {
   BlockNode block(false);  // Default response.
 
-  for (size_t i = 0; i < pending_.size(); i++) {
-    CannedResponseMap::const_iterator found =
-        canned_responses_.find(pending_[i].first);
+  for (const auto& cur : pending_) {
+    CannedResponseMap::const_iterator found = canned_responses_.find(cur.first);
     if (found == canned_responses_.end())
-      pending_[i].second.Run(&block);
+      cur.second.Run(&block);
     else
-      pending_[i].second.Run(found->second->root.get());
+      cur.second.Run(found->second->root.get());
   }
   pending_.clear();
 }