Don't generate LASTCHANGE at build time.

tools/export_tarball/export_tarball.py

 #!/usr/bin/env python
-# Copyright (c) 2011 The Chromium Authors. All rights reserved.
+# Copyright (c) 2012 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.
 
 """
 This tool creates a tarball with all the sources, but without .svn directories.
 
 It can also remove files which are not strictly required for build, so that
 the resulting tarball can be reasonably small (last time it was ~110 MB).
 
 Example usage:
@@ skipping 81 matching lines @@
 
   if len(args) != 1:
     print 'You must provide only one argument: output file name'
     print '(without .tar.bz2 extension).'
     return 1
 
   if not os.path.exists(GetSourceDirectory()):
     print 'Cannot find the src directory.'
     return 1
 
+  # This command is from src/DEPS; please keep them in sync.
+  if subprocess.call(['python', 'build/util/lastchange.py', '-o',
+                      'build/util/LASTCHANGE'], cwd=GetSourceDirectory()) != 0:
+    print 'Could not run build/util/lastchange.py to update LASTCHANGE.'
+    return 1
+
   output_fullname = args[0] + '.tar.bz2'
   output_basename = os.path.basename(args[0])
 
   archive = MyTarFile.open(output_fullname, 'w:bz2')
   archive.set_remove_nonessential_files(options.remove_nonessential_files)
   try:
     archive.add(GetSourceDirectory(), arcname=output_basename)
   finally:
     archive.close()
 
   return 0
 
 
 if __name__ == "__main__":
   sys.exit(main(sys.argv[1:]))