Add support for data deps.

tools/gn/ninja_target_writer.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TOOLS_GN_NINJA_TARGET_WRITER_H_
 #define TOOLS_GN_NINJA_TARGET_WRITER_H_
 
 #include <iosfwd>
 #include <string>
 
@@ skipping 31 matching lines @@
   void WriteCustomSourceRules(const std::string& custom_rule_name,
                               const std::string& common_deps,
                               const SourceDir& script_cd,
                               const std::string& script_cd_to_root,
                               std::vector<OutputFile>* output_files);
 
   void WriteCompilerVars();
   void WriteSources(std::vector<OutputFile>* object_files);
   void WriteLinkerStuff(const std::vector<OutputFile>& object_files);
 
+  // Writes the build line for linking the target. Includes newline.
+  void WriteLinkCommand(const OutputFile& external_output_file,
+                        const OutputFile& internal_output_file,
+                        const std::vector<OutputFile>& object_files);
+
   // Returns NULL if the source type should not be compiled on this target.
   const char* GetCommandForSourceType(SourceFileType type) const;
 
   const char* GetCommandForTargetType() const;
 
   const Settings* settings_;  // Non-owning.
   const Target* target_;  // Non-owning.
   std::ostream& out_;
   PathOutput path_output_;
 
   NinjaHelper helper_;
 
   DISALLOW_COPY_AND_ASSIGN(NinjaTargetWriter);
 };
 
 #endif  // TOOLS_GN_NINJA_TARGET_WRITER_H_