Rename roll-dep to roll-dep-svn and add roll-dep for git.

roll_dep_svn.py

 #!/usr/bin/env python
 # Copyright (c) 2014 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 scripts takes the path to a dep and a git or svn revision, and updates
-the parent repo's DEPS file with the corresponding git revision.  Sample
-invocation:
+"""Rolls a git-svn dependency.
 
-[chromium/src]$ roll-dep third_party/WebKit 12345
+It takes the path to a dep and a git commit hash or svn revision, and updates
+the parent repo's DEPS file with the corresponding git commit hash.
+
+Sample invocation:
+
+[chromium/src]$ roll-dep-svn third_party/WebKit 12345
 
 After the script completes, the DEPS file will be dirty with the new revision.
 The user can then:
 
 $ git add DEPS
 $ git commit
 """
 
 import ast
 import optparse
@@ skipping 332 matching lines @@
   deps_file_dir = os.path.normpath(os.path.dirname(deps_file))
   deps_file_root = Popen(
       ['git', 'rev-parse', '--show-toplevel'],
       cwd=deps_file_dir, stdout=PIPE).communicate()[0].strip()
   with open(os.path.join(deps_file_root, '.git', 'MERGE_MSG'), 'w') as fh:
     fh.write(commit_msg)
   return 0
 
 
 def main(argv):
-  usage = 'Usage: roll_dep.py [options] <dep path> <rev> [ <DEPS file> ]'
+  usage = 'Usage: roll-dep-svn [options] <dep path> <rev> [ <DEPS file> ]'
   parser = optparse.OptionParser(usage=usage, description=__doc__)
   parser.add_option('--no-verify-revision',
                     help='Don\'t verify the revision passed in. This '
                          'also skips adding an svn revision comment '
                          'for git dependencies and requires the passed '
                          'revision to be a git hash.',
                     default=False, action='store_true')
   options, args = parser.parse_args(argv)
   if len(args) not in (2, 3):
     parser.error('Expected either 2 or 3 positional parameters.')
@@ skipping 31 matching lines @@
       return 1
   return update_deps(deps_file, dep_path, dep_name, git_rev, comment)
 
 
 if __name__ == '__main__':
   try:
     sys.exit(main(sys.argv[1:]))
   except KeyboardInterrupt:
     sys.stderr.write('interrupted\n')
     sys.exit(1)