Add full_move flag to GIT.GenerateDiff and Factor out FindGclientRootDir into gclient_utils.

tests/trychange_unittest.py

 #!/usr/bin/python
 # Copyright (c) 2009 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.
 
 """Unit tests for trychange.py."""
 
 import optparse
 
 # Local imports
@@ skipping 65 matching lines @@
   def testMembersChanged(self):
     members = [
       'GetBots', 'GetFileNames', 'GetLocalRoot',
     ]
     # If this test fails, you should add the relevant test.
     self.compareMembers(trychange.GIT, members)
 
   def testBasic(self):
     trychange.os.getcwd().AndReturn(self.fake_root)
     trychange.scm.GIT.GetCheckoutRoot(self.fake_root).AndReturn(self.fake_root)
-    trychange.scm.GIT.GenerateDiff(self.fake_root).AndReturn('a diff')
+    trychange.scm.GIT.GenerateDiff(self.fake_root,
+                                   full_move=True).AndReturn('a diff')
     trychange.scm.GIT.GetPatchName(self.fake_root).AndReturn('bleh-1233')
     trychange.scm.GIT.GetEmail(self.fake_root).AndReturn('georges@example.com')
     self.mox.ReplayAll()
     git = trychange.GIT(self.options)
     self.assertEqual(git.GetFileNames(), self.expected_files)
     self.assertEqual(git.GetLocalRoot(), self.fake_root)
 
 
 if __name__ == '__main__':
   import unittest
   unittest.main()