Refactor GN source expansions.

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 e5ece40fae48f7d0097872a1dfba4d8efbde6275..f18a2b1a1aa730f58c0da0742e6f367b77db6181 100644
--- a/tools/gn/ninja_action_target_writer.h
+++ b/tools/gn/ninja_action_target_writer.h
@@ -11,7 +11,6 @@
 #include "base/gtest_prod_util.h"
 #include "tools/gn/ninja_target_writer.h"
 
-class FileTemplate;
 class OutputFile;
 
 // Writes a .ninja file for a action target type.
@@ -39,7 +38,7 @@ class NinjaActionTargetWriter : public NinjaTargetWriter {
   // Returns the name of the custom rule generated. This will be based on the
   // target name, and will include the string "$unique_name" if there are
   // multiple inputs.
-  std::string WriteRuleDefinition(const FileTemplate& args_template);
+  std::string WriteRuleDefinition();
 
   // Writes the rules for compiling each source, writing all output files
   // to the given vector.
@@ -48,14 +47,8 @@ class NinjaActionTargetWriter : public NinjaTargetWriter {
   // to each build step, it starts with a "|" if it's nonempty.
   void WriteSourceRules(const std::string& custom_rule_name,
                         const std::string& implicit_deps,
-                        const FileTemplate& args_template,
                         std::vector<OutputFile>* output_files);
 
-  // Writes the Ninja variables that expand the substitutions required by the
-  // arguments for the given source file.
-  void WriteArgsSubstitutions(const SourceFile& source,
-                              const FileTemplate& args_template);
-
   // 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);
@@ -63,15 +56,11 @@ class NinjaActionTargetWriter : public NinjaTargetWriter {
   // 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.
-  void WriteOutputFilesForBuildLine(const FileTemplate& output_template,
-                                    const SourceFile& source,
+  void WriteOutputFilesForBuildLine(const SourceFile& source,
                                     std::vector<OutputFile>* output_files);
 
   void WriteDepfile(const SourceFile& source);
 
-  // Returns the FileTemplate for the depfile variable.
-  FileTemplate GetDepfileTemplate() const;
-
   // Path output writer that doesn't do any escaping or quoting. It does,
   // however, convert slashes.  Used for
   // computing intermediate strings.