Factor out gcl.GetRepositoryRoot() into scm.SVN.GetCheckoutRoot()

This is to reduce trychange.py dependency on gcl.py

Review URL: http://codereview.chromium.org/502085

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@35055 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/tests/gclient_scm_test.py b/tests/gclient_scm_test.py
index 99b4a9e..f862319 100755
--- a/tests/gclient_scm_test.py
+++ b/tests/gclient_scm_test.py
@@ -65,7 +65,7 @@
   def testDir(self):
     members = [
         'COMMAND', 'Capture', 'CaptureHeadRevision', 'CaptureInfo',
-        'CaptureStatus', 'DiffItem', 'GetEmail',
+        'CaptureStatus', 'DiffItem', 'GetCheckoutRoot', 'GetEmail',
         'GetFileProperty', 'IsMoved', 'ReadSimpleAuth', 'Run',
         'RunAndFilterOutput', 'RunAndGetFileList',
         'RunCommand', 'cleanup', 'diff', 'export', 'pack', 'relpath', 'revert',