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

tools/gn/command_desc.cc

 // 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.
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <set>
 #include <sstream>
 
@@ skipping 319 matching lines @@
 
   if (target->output_type() == Target::ACTION) {
     // Action, print out outputs, don't apply sources to it.
     for (const auto& elem : target->action_values().outputs().list()) {
       OutputString("  " + elem.AsString() + "\n");
     }
   } else if (target->output_type() == Target::CREATE_BUNDLE) {
     std::vector<SourceFile> output_files;
     target->bundle_data().GetOutputsAsSourceFiles(target->settings(),
                                                   &output_files);
-    PrintFileList(output_files, "", true, false);
+    PrintFileList(output_files, std::string(), true, false);
   } else {
     const SubstitutionList& outputs = target->action_values().outputs();
     if (!outputs.required_types().empty()) {
       // Display the pattern and resolved pattern separately, since there are
       // subtitutions used.
       OutputString("  Output pattern\n");
       for (const auto& elem : outputs.list())
         OutputString("    " + elem.AsString() + "\n");
 
       // Now display what that resolves to given the sources.
       OutputString("\n  Resolved output file list\n");
     }
 
     // Resolved output list.
     std::vector<SourceFile> output_files;
     SubstitutionWriter::ApplyListToSources(target->settings(), outputs,
                                            target->sources(), &output_files);
-    PrintFileList(output_files, "", true, false);
+    PrintFileList(output_files, std::string(), true, false);
   }
 }
 
 void PrintScript(const Target* target, bool display_header) {
   if (display_header)
     OutputString("\nscript\n");
   OutputString("  " + target->action_values().script().value() + "\n");
 }
 
 void PrintArgs(const Target* target, bool display_header) {
@@ skipping 555 matching lines @@
     printed_output = true;
 
     if (!PrintConfig(config, what_to_print, display_item_header))
       return 1;
   }
 
   return 0;
 }
 
 }  // namespace commands