Fix autoroller in accordance to upstream change

tools_webrtc/autoroller/unittests/roll_deps_test.py

Index: tools_webrtc/autoroller/unittests/roll_deps_test.py
diff --git a/tools_webrtc/autoroller/unittests/roll_deps_test.py b/tools_webrtc/autoroller/unittests/roll_deps_test.py
index 65b5288b0b2d65b7d05509fbf72a2e9495ad7b12..dc2bacd3850b34b9bef5400171b81d9e5b2853f4 100755
--- a/tools_webrtc/autoroller/unittests/roll_deps_test.py
+++ b/tools_webrtc/autoroller/unittests/roll_deps_test.py
@@ -82,6 +82,11 @@ class TestRollChromiumRevision(unittest.TestCase):
     self.assertEqual(self.fake.expectations, [])
     setattr(roll_deps, '_RunCommand', self.old_run_command)
 
+  def testVarLookup(self):
+    local_scope = {'foo': 'wrong', 'vars': {'foo': 'bar'}}
+    lookup = roll_deps.VarLookup(local_scope)
+    self.assertEquals(lookup('foo'), 'bar')
+
   def testUpdateDepsFile(self):
     new_rev = 'aaaaabbbbbcccccdddddeeeeefffff0000011111'