Import w3c tests for the service workers

third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/ServiceWorkerGlobalScope/resources/update-worker.py

+import os
+import time
+
+def main(request, response):
+    # update() does not bypass cache so set the max-age to 0 such that update()
+    # can find a new version in the network.
+    headers = [('Cache-Control', 'max-age: 0'),
+               ('Content-Type', 'application/javascript')]
+    with open(os.path.join(os.path.dirname(__file__),
+                           'update-worker.js'), 'r') as file:
+        script = file.read()
+    # Return a different script for each access.
+    return headers, '// %s\n%s' % (time.time(), script)
+