Revert of Revert "[telemetry] Wire TsProxy through telemetry's network stack."

telemetry/telemetry/testing/serially_executed_browser_test_case.py

Index: telemetry/telemetry/testing/serially_executed_browser_test_case.py
diff --git a/telemetry/telemetry/testing/serially_executed_browser_test_case.py b/telemetry/telemetry/testing/serially_executed_browser_test_case.py
index 4799a96b3d81b9b2f839fc0ee2220ee3a3f0cec0..75bf2002e911d73b1354fcfa621eb1a6d25bf773 100644
--- a/telemetry/telemetry/testing/serially_executed_browser_test_case.py
+++ b/telemetry/telemetry/testing/serially_executed_browser_test_case.py
@@ -46,6 +46,7 @@
     cls._browser_to_create = browser_finder.FindBrowser(browser_options)
     if not cls.platform:
       cls.platform = cls._browser_to_create.platform
+      cls.platform.network_controller.InitializeIfNeeded()
     else:
       assert cls.platform == cls._browser_to_create.platform, (
           'All browser launches within same test suite must use browsers on '
@@ -92,6 +93,7 @@
   def tearDownClass(cls):
     if cls.platform:
       cls.platform.StopAllLocalServers()
+      cls.platform.network_controller.Close()
     if cls.browser:
       cls.StopBrowser()