Revert of [Telemetry] Modify CreatePageSet to CreateStorySet

tools/telemetry/telemetry/benchmark.py

Index: tools/telemetry/telemetry/benchmark.py
diff --git a/tools/telemetry/telemetry/benchmark.py b/tools/telemetry/telemetry/benchmark.py
index 0c94fc1ef004f68d64c1afb5cf71864ed229e2cf..7f3f1aefb0dc5ed6ac1420da3ca693b912cdfe32 100644
--- a/tools/telemetry/telemetry/benchmark.py
+++ b/tools/telemetry/telemetry/benchmark.py
@@ -11,6 +11,7 @@
 from telemetry.internal import story_runner
 from telemetry.internal.util import exception_formatter
 from telemetry import page
+from telemetry.page import page_set
 from telemetry.page import page_test
 from telemetry.page import test_expectations
 from telemetry.web_perf import timeline_based_measurement
@@ -241,17 +242,24 @@
     self.SetupTraceRerunOptions(options, opts)
     return timeline_based_measurement.TimelineBasedMeasurement(opts)
 
+  def CreatePageSet(self, options):  # pylint: disable=unused-argument
+    """Get the page set this test will run on.
+
+    By default, it will create a page set from the this test's page_set
+    attribute. Override to generate a custom page set.
+    """
+    if not hasattr(self, 'page_set'):
+      raise NotImplementedError('This test has no "page_set" attribute.')
+    if not issubclass(self.page_set, page_set.PageSet):
+      raise TypeError('"%s" is not a PageSet.' % self.page_set.__name__)
+    return self.page_set()
+
   def CreateStorySet(self, options):
     """Creates the instance of StorySet used to run the benchmark.
 
     Can be overridden by subclasses.
     """
-    del options  # unused
-    # TODO(aiolos, nednguyen, eakufner): replace class attribute page_set with
-    # story_set.
-    if not hasattr(self, 'page_set'):
-      raise NotImplementedError('This test has no "page_set" attribute.')
-    return self.page_set()
+    return self.CreatePageSet(options)
 
   @classmethod
   def CreateExpectations(cls):