Stop the existing session if it exists before start a new session and add mirroring scenario for cp…

chrome/test/media_router/telemetry/benchmarks/pagesets/media_router_perf_pages.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import utils
 
 from telemetry import page
 from telemetry import story
 from benchmarks.pagesets import media_router_page
 from telemetry.core import exceptions
@@ skipping 165 matching lines @@
     self.AddStory(CastDialogPage(self))
 
 
 class MediaRouterCPUMemoryPageSet(story.StorySet):
   """Pageset for media router CPU/memory usage tests."""
 
   def __init__(self):
     super(MediaRouterCPUMemoryPageSet, self).__init__(
         cloud_storage_bucket=story.PARTNER_BUCKET)
     self.AddStory(CastIdlePage(self))
-    self.AddStory(CastFlingingPage(self))
-    self.AddStory(CastMirroringPage(self))
+    #self.AddStory(CastFlingingPage(self))
+    #self.AddStory(CastMirroringPage(self))
+
+
+class CPUMemoryPageSet(story.StorySet):
+  """Pageset for media router CPU/memory usage tests."""
+
+  def __init__(self):
+    super(CPUMemoryPageSet, self).__init__(
+        cloud_storage_bucket=story.PARTNER_BUCKET)
+    self.AddStory(CastIdlePage(self))