Add support for python pageset

tools/telemetry/telemetry/core/discover_unittest.py

Index: tools/telemetry/telemetry/core/discover_unittest.py
diff --git a/tools/telemetry/telemetry/core/discover_unittest.py b/tools/telemetry/telemetry/core/discover_unittest.py
index 34bc8914006da6e90ce77c222ef441499066a68c..c3df4a40f876d56bd25ff46666663da2a54cf903 100644
--- a/tools/telemetry/telemetry/core/discover_unittest.py
+++ b/tools/telemetry/telemetry/core/discover_unittest.py
@@ -50,3 +50,14 @@ class DiscoverTest(unittest.TestCase):
         'dummy_exception_impl2': 'DummyExceptionImpl2',
     }
     self.assertEqual(actual_classes, expected_classes)
+
+  def testIsPageSetFile(self):
+    top_10_ps_dir = os.path.join(util.GetChromiumSrcDir(),
+                                 'tools/perf/page_sets/top_10.py')
+    test_ps_dir = os.path.join(util.GetTelemetryDir(),
+                               'unittest_data/test_page_set.py')
+    page_set_dir = os.path.join(util.GetTelemetryDir(),
+                               'telemetry/page/page_set.py')
+    self.assertTrue(discover.IsPageSetFile(top_10_ps_dir))
+    self.assertFalse(discover.IsPageSetFile(test_ps_dir))
+    self.assertFalse(discover.IsPageSetFile(page_set_dir))