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

roll_dep_svn.py

Index: roll_dep_svn.py
diff --git a/roll_dep.py b/roll_dep_svn.py
similarity index 97%
copy from roll_dep.py
copy to roll_dep_svn.py
index 2e38b04d1aa64c530a7b4c944c31ae80d8dfaaf2..d7af5eb43c93cf64bef6b1752224905415ff6949 100755
--- a/roll_dep.py
+++ b/roll_dep_svn.py
@@ -3,11 +3,14 @@
 # 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:
@@ -360,7 +363,7 @@ def update_deps(deps_file, dep_path, dep_name, new_rev, comment):
 
 
 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 '