Enable media_cns_cases on Linux (Android is excluded on the bot).

tools/perf/benchmarks/media.py

 # Copyright 2013 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 platform
 import sys
 
 from measurements import media
 from telemetry import test
 
 class Media(test.Test):
   """Obtains media metrics for key user scenarios."""
   test = media.Media
   # Disable on Win8 crbug.com/326384
   win8 = sys.platform.startswith('win') and '2008' in platform.release()
   enabled = not win8
   page_set = 'page_sets/tough_video_cases.json'
 
 class MediaNetworkSimulation(test.Test):
   """Obtains media metrics under different network simulations."""
   test = media.Media
-  enabled = not sys.platform.startswith('linux')
   page_set = 'page_sets/media_cns_cases.json'
 
 class MediaAndroid(test.Test):
   """Obtains media metrics for key user scenarios on Android."""
   test = media.Media
   tag = 'android'
   page_set = 'page_sets/tough_video_cases.json'
   # Exclude crowd* media files (50fps 2160p).
   options = {
       'page_filter_exclude': '.*crowd.*'
   }
 
   def CustomizeBrowserOptions(self, options):
     # Needed to run media actions in JS in Android.
     options.AppendExtraBrowserArgs(
         '--disable-gesture-requirement-for-media-playback')
 
 class MediaSourceExtensions(test.Test):
   """Obtains media metrics for key media source extensions functions."""
   test = media.Media
   page_set = 'page_sets/mse_cases.json'
 
   def CustomizeBrowserOptions(self, options):
     # Needed to allow XHR requests to return stream objects.
     options.AppendExtraBrowserArgs(
         '--enable-experimental-web-platform-features')