[GN] Add support for code signing to "create_bundle" targets.

tools/gn/ninja_create_bundle_target_writer.h

Index: tools/gn/ninja_create_bundle_target_writer.h
diff --git a/tools/gn/ninja_create_bundle_target_writer.h b/tools/gn/ninja_create_bundle_target_writer.h
index 42b900f6bc2a0ff98f67abd4bf09f89cff9c3f98..7c4239c05f8095ed4467aeb83dd3b70a7b993c86 100644
--- a/tools/gn/ninja_create_bundle_target_writer.h
+++ b/tools/gn/ninja_create_bundle_target_writer.h
@@ -17,6 +17,41 @@ class NinjaCreateBundleTargetWriter : public NinjaTargetWriter {
   void Run() override;
 
  private:
+  // Writes the Ninja rule for invoking the code signing script.
+  //
+  // Returns the name of the custom rule generated for the code signing step if
+  // defined, otherwise returns an empty string.
+  std::string WriteCodeSigningRuleDefinition();
+
+  // Writes the rule to copy files into the bundle.
+  //
+  // input_dep is a file expressing the shared dependencies. It will be a
+  // stamp file if there is more than one.
+  void WriteCopyBundleDataRules(const OutputFile& input_dep,
+                                std::vector<OutputFile>* output_files);
+
+  // Writes the rule to compile assets catalogs.
+  //
+  // input_dep is a file expressing the shared dependencies. It will be a
+  // stamp file if there is more than one.
+  void WriteCompileAssetsCatalogRule(const OutputFile& input_dep,
+                                     std::vector<OutputFile>* output_files);
+
+  // Writes the code signing rule (if a script is defined).
+  //
+  // input_dep is a file expressing the shared dependencies. It will be a
+  // stamp file if there is more than one. As the code signing may include
+  // a manifest of the file, this will depends on all files in output_files
+  // too.
+  void WriteCodeSigningRules(const std::string& code_signing_rule_name,
+                             const OutputFile& input_dep,
+                             std::vector<OutputFile>* output_files);
+
+  // Writes the stamp file for the code signing input dependencies.
+  OutputFile WriteCodeSigningInputDepsStamp(
+      const OutputFile& input_dep,
+      std::vector<OutputFile>* output_files);
+
   DISALLOW_COPY_AND_ASSIGN(NinjaCreateBundleTargetWriter);
 };