Group SCM-specific functions in classes to simplify generalization of the interface.

git_cl_hooks.py

Index: git_cl_hooks.py
diff --git a/git_cl_hooks.py b/git_cl_hooks.py
index 5203096f544f6bfde174223ef60a957a939eb7eb..53808d26abefbecd3904c4b512d9e3c74ca58817 100644
--- a/git_cl_hooks.py
+++ b/git_cl_hooks.py
@@ -7,9 +7,8 @@ import re
 import subprocess
 import sys
 
-# Imported from depot_tools.
-import gclient_scm
 import presubmit_support
+import scm
 
 def Backquote(cmd, cwd=None):
   """Like running `cmd` in a shell script."""
@@ -35,8 +34,8 @@ class ChangeOptions:
       raise Exception("Could not parse log message: %s" % log)
     name = m.group(1)
     description = m.group(2)
-    files = gclient_scm.CaptureGitStatus([root], upstream_branch)
-    issue = Backquote(['git', 'cl', 'status', '--field=id'])
+    files = scm.GIT.CaptureStatus([root], upstream_branch)
+    issue = Backquote(['cl', 'status', '--field=id'])
     patchset = None
     self.change = presubmit_support.GitChange(name, description, root, files,
                                               issue, patchset)