telemetry: Replace mostly_smooth by percentage_smooth.

tools/perf/measurements/repaint_unittest.py

Index: tools/perf/measurements/repaint_unittest.py
diff --git a/tools/perf/measurements/repaint_unittest.py b/tools/perf/measurements/repaint_unittest.py
index 33c8cfc5d618da0d031ba573be94816e548e3a11..40a910f45f1fbccb6c61a810702ae88f67e0bfd2 100644
--- a/tools/perf/measurements/repaint_unittest.py
+++ b/tools/perf/measurements/repaint_unittest.py
@@ -50,9 +50,10 @@ class RepaintUnitTest(page_test_test_case.PageTestTestCase):
     self.assertEquals(len(jank), 1)
     self.assertGreater(jank[0].GetRepresentativeNumber(), 0)
 
-    mostly_smooth = results.FindAllPageSpecificValuesNamed('mostly_smooth')
-    self.assertEquals(len(mostly_smooth), 1)
-    self.assertGreaterEqual(mostly_smooth[0].GetRepresentativeNumber(), 0)
+    percentage_smooth = results.FindAllPageSpecificValuesNamed(
+        'percentage_smooth')
+    self.assertEquals(len(percentage_smooth), 1)
+    self.assertGreaterEqual(percentage_smooth[0].GetRepresentativeNumber(), 0)
 
   @test.Disabled('android')
   def testCleanUpTrace(self):