Support script response files in GN.

tools/gn/action_values.h

Index: tools/gn/action_values.h
diff --git a/tools/gn/action_values.h b/tools/gn/action_values.h
index 3b3c2a62197f559dd0b52bef4378ea347cdb7dd9..879ccf6ef694a315c820c0d6e3bf5d107436293e 100644
--- a/tools/gn/action_values.h
+++ b/tools/gn/action_values.h
@@ -43,6 +43,13 @@ class ActionValues {
   bool has_depfile() const { return !depfile_.ranges().empty(); }
   void set_depfile(const SubstitutionPattern& depfile) { depfile_ = depfile; }
 
+  // Response file contents. Empty means no response file.
+  SubstitutionList& rsp_file_contents() { return rsp_file_contents_; }
+  const SubstitutionList& rsp_file_contents() const {
+    return rsp_file_contents_;
+  }
+  bool uses_rsp_file() const { return !rsp_file_contents_.list().empty(); }
+
   // Console pool option
   bool is_console() const { return console_; }
   void set_console(bool value) { console_ = value; }
@@ -52,6 +59,7 @@ class ActionValues {
   SubstitutionList args_;
   SubstitutionList outputs_;
   SubstitutionPattern depfile_;
+  SubstitutionList rsp_file_contents_;
   bool console_;
 
   DISALLOW_COPY_AND_ASSIGN(ActionValues);