add polymer pageset to smoothness benchmark

R=dtu@chromium.org
BUG=

Review URL: https://codereview.chromium.org/255063003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266802 0039d316-1c4b-4281-b951-d872f2087c98

tools/perf/benchmarks/smoothness.py

@@ -116,3 +116,10 @@ class SmoothnessToughPinchZoomCases(test.Test):
   """
   test = smoothness.Smoothness
   page_set = 'page_sets/tough_pinch_zoom_cases.py'
+
+
+class SmoothnessPolymer(test.Test):
+  """Measures rendering statistics for Polymer cases.
+  """
+  test = smoothness.Smoothness
+  page_set = 'page_sets/polymer.py'
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