Fix GN action target writing with no sources list.

tools/gn/function_get_target_outputs.cc

Index: tools/gn/function_get_target_outputs.cc
diff --git a/tools/gn/function_get_target_outputs.cc b/tools/gn/function_get_target_outputs.cc
index d711428d2e5d2c35a99502f1a5ffe405b6f83e65..c8fedb9bcd0374f0dc1b21d831311440eaf1393b 100644
--- a/tools/gn/function_get_target_outputs.cc
+++ b/tools/gn/function_get_target_outputs.cc
@@ -20,13 +20,11 @@ void GetOutputsForTarget(const Settings* settings,
                          std::vector<SourceFile>* ret) {
   switch (target->output_type()) {
     case Target::ACTION: {
-      // Actions just use the output list with no substitution. To keep things
-      // simple, pass an empty "source file" in to use the same code path for
-      // computing substitution outputs.
+      // Actions just use the output list with no substitution.
       std::vector<SourceFile> sources;
       sources.push_back(SourceFile());
-      SubstitutionWriter::ApplyListToSources(
-          settings, target->action_values().outputs(), sources, ret);
+      SubstitutionWriter::GetListAsSourceFiles(
+          settings, target->action_values().outputs(), ret);
       break;
     }