Update CNS to run on chromeperf34 and CNS tests to run on windows perf_av bot.

chrome/test/functional/media/media_constrained_network_perf.py

Index: chrome/test/functional/media/media_constrained_network_perf.py
diff --git a/chrome/test/functional/media/media_constrained_network_perf.py b/chrome/test/functional/media/media_constrained_network_perf.py
index d78567f6c9dbc15e9c65cdc0697524aa85091a74..d06b82d10c6e45a339b72c4c7aac922ec1056e0c 100755
--- a/chrome/test/functional/media/media_constrained_network_perf.py
+++ b/chrome/test/functional/media/media_constrained_network_perf.py
@@ -21,6 +21,7 @@ The CNS code is located under: <root>/src/media/tools/constrained_network_server
 
 import logging
 import os
+import posixpath
 import Queue
 
 import pyauto_media
@@ -54,14 +55,14 @@ _TEST_ITERATIONS = 3
 
 # Media file names used for measuring epp and tpp.
 _TEST_MEDIA_EPP = ['roller.webm']
-_TEST_MEDIA_EPP.extend(os.path.join('crowd', name) for name in
+_TEST_MEDIA_EPP.extend(posixpath.join('crowd', name) for name in
                        ['crowd360.ogv', 'crowd.wav', 'crowd.ogg'])
 
 # Media file names used for measuring tpp without epp.
-_TEST_MEDIA_NO_EPP = [os.path.join('dartmoor', name) for name in
+_TEST_MEDIA_NO_EPP = [posixpath.join('dartmoor', name) for name in
                       ['dartmoor2.ogg', 'dartmoor2.m4a', 'dartmoor2.mp3',
                        'dartmoor2.wav']]
-_TEST_MEDIA_NO_EPP.extend(os.path.join('crowd', name) for name in
+_TEST_MEDIA_NO_EPP.extend(posixpath.join('crowd', name) for name in
                           ['crowd1080.webm', 'crowd1080.ogv', 'crowd1080.mp4',
                            'crowd360.webm', 'crowd360.mp4'])