GN: Bug fixes in process_file_template

tools/gn/substitution_writer.h

Index: tools/gn/substitution_writer.h
diff --git a/tools/gn/substitution_writer.h b/tools/gn/substitution_writer.h
index 2bc9ed2aa86ebe3e41af2a6a9dd9e3f783ef7d9b..dd8f77aa34a586491325bf086977a234c9fd92c2 100644
--- a/tools/gn/substitution_writer.h
+++ b/tools/gn/substitution_writer.h
@@ -34,11 +34,18 @@ class SubstitutionWriter {
   ~SubstitutionWriter();
 
   // Applies the substitution pattern to a source file, returning the result
-  // as either a SourceFile or OutputFile.
+  // as either a string, a SourceFile or an OutputFile. If the result is
+  // expected to be a SourceFile or an OutputFile, this will CHECK if the
+  // result isn't in the correct directory. The caller should validate this
+  // first (see for example IsFileInOuputDir).
   static SourceFile ApplyPatternToSource(
       const Settings* settings,
       const SubstitutionPattern& pattern,
       const SourceFile& source);
+  static std::string ApplyPatternToSourceAsString(
+      const Settings* settings,
+      const SubstitutionPattern& pattern,
+      const SourceFile& source);
   static OutputFile ApplyPatternToSourceAsOutputFile(
       const Settings* settings,
       const SubstitutionPattern& pattern,
@@ -53,6 +60,11 @@ class SubstitutionWriter {
       const SubstitutionList& list,
       const SourceFile& source,
       std::vector<SourceFile>* output);
+  static void ApplyListToSourceAsString(
+      const Settings* settings,
+      const SubstitutionList& list,
+      const SourceFile& source,
+      std::vector<std::string>* output);
   static void ApplyListToSourceAsOutputFile(
       const Settings* settings,
       const SubstitutionList& list,
@@ -66,6 +78,11 @@ class SubstitutionWriter {
       const SubstitutionList& list,
       const std::vector<SourceFile>& sources,
       std::vector<SourceFile>* output);
+  static void ApplyListToSourcesAsString(
+      const Settings* settings,
+      const SubstitutionList& list,
+      const std::vector<SourceFile>& sources,
+      std::vector<std::string>* output);
   static void ApplyListToSourcesAsOutputFile(
       const Settings* settings,
       const SubstitutionList& list,