Add support for module-definition files to gn

tools/gn/ninja_binary_target_writer.h

Index: tools/gn/ninja_binary_target_writer.h
diff --git a/tools/gn/ninja_binary_target_writer.h b/tools/gn/ninja_binary_target_writer.h
index 22d2332c8f409c9a5d852128bedb43fb76ef3d00..5c930cbf8df109c317d578ee5ded1520c0c4dd05 100644
--- a/tools/gn/ninja_binary_target_writer.h
+++ b/tools/gn/ninja_binary_target_writer.h
@@ -26,9 +26,11 @@ class NinjaBinaryTargetWriter : public NinjaTargetWriter {
   typedef std::set<OutputFile> OutputFileSet;
 
   void WriteCompilerVars();
-  void WriteSources(std::vector<OutputFile>* object_files);
-  void WriteLinkerStuff(const std::vector<OutputFile>& object_files);
-  void WriteLinkerFlags();
+  void WriteSources(std::vector<OutputFile>* object_files,
+                    std::vector<SourceFile>* other_files);
+  void WriteLinkerStuff(const std::vector<OutputFile>& object_files,
+                        const std::vector<SourceFile>& other_files);
+  void WriteLinkerFlags(const SourceFile* def_file);

[brettw, 2015/05/27 17:27:00]

Maybe call this variable optional_def_file so it's more clear that it can be
null?

   void WriteLibs();
   void WriteOutputExtension();
   void WriteSolibs(const std::vector<OutputFile>& solibs);