Support more configurability in GN toolchains

tools/gn/ninja_action_target_writer.h

Index: tools/gn/ninja_action_target_writer.h
diff --git a/tools/gn/ninja_action_target_writer.h b/tools/gn/ninja_action_target_writer.h
index f18a2b1a1aa730f58c0da0742e6f367b77db6181..b440ac224935a458548a9ee372a84cac74f234e9 100644
--- a/tools/gn/ninja_action_target_writer.h
+++ b/tools/gn/ninja_action_target_writer.h
@@ -16,9 +16,7 @@ class OutputFile;
 // Writes a .ninja file for a action target type.
 class NinjaActionTargetWriter : public NinjaTargetWriter {
  public:
-  NinjaActionTargetWriter(const Target* target,
-                          const Toolchain* toolchain,
-                          std::ostream& out);
+  NinjaActionTargetWriter(const Target* target, std::ostream& out);
   virtual ~NinjaActionTargetWriter();
 
   virtual void Run() OVERRIDE;
@@ -31,8 +29,6 @@ class NinjaActionTargetWriter : public NinjaTargetWriter {
   FRIEND_TEST_ALL_PREFIXES(NinjaActionTargetWriter,
                            WriteArgsSubstitutions);
 
-  bool has_sources() const { return !target_->sources().empty(); }
-
   // Writes the Ninja rule for invoking the script.
   //
   // Returns the name of the custom rule generated. This will be based on the
@@ -49,10 +45,6 @@ class NinjaActionTargetWriter : public NinjaTargetWriter {
                         const std::string& implicit_deps,
                         std::vector<OutputFile>* output_files);
 
-  // Writes the .stamp rule that names this target and collects all invocations
-  // of the script into one thing that other targets can depend on.
-  void WriteStamp(const std::vector<OutputFile>& output_files);
-
   // Writes the output files generated by the output template for the given
   // source file. This will start with a space and will not include a newline.
   // Appends the output files to the given vector.