GN: Change gen command syntax, support relative dirs.

tools/gn/command_refs.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 <set>
 
 #include "base/command_line.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/input_file.h"
@@ skipping 67 matching lines @@
           "or it can never match anything.\nTo match a substring, use "
           "\"*foo*\".").PrintToStdout();
       return 1;
     }
   }
 
   Pattern pattern(args[0]);
 
   Setup* setup = new Setup;
   setup->set_check_for_bad_items(false);
-  if (!setup->DoSetup() || !setup->Run())
+  // TODO(brettw) bug 343726: Use a temporary directory instead of this
+  // default one to avoid messing up any build that's in there.
+  if (!setup->DoSetup("//out/Default/") || !setup->Run())
     return 1;
 
   std::vector<const BuilderRecord*> records = setup->builder()->GetAllRecords();
 
   const CommandLine* cmdline = CommandLine::ForCurrentProcess();
 
   bool file_output = cmdline->HasSwitch("files");
   std::set<std::string> unique_output;
 
   for (size_t record_index = 0; record_index < records.size(); record_index++) {
@@ skipping 19 matching lines @@
   }
 
   for (std::set<std::string>::iterator i = unique_output.begin();
        i != unique_output.end(); ++i)
     OutputString(*i + "\n");
 
   return 0;
 }
 
 }  // namespace commands