[telemetry] Refactor run_tests to remove old cruft.

tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py

Index: tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py b/tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py
index b482a6a60692962c5497148e60420f466ff7b0ae..fddff999446a853f28aee6ddabdf98d530c50687 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/cros_browser_backend.py
@@ -16,15 +16,13 @@ from telemetry.core.forwarders import cros_forwarder
 
 
 class CrOSBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
-  def __init__(self, browser_type, browser_options, cri, is_guest,
-               extensions_to_load):
+  def __init__(self, browser_options, cri, is_guest, extensions_to_load):
     super(CrOSBrowserBackend, self).__init__(
         supports_tab_control=True, supports_extensions=not is_guest,
         browser_options=browser_options,
         output_profile_path=None, extensions_to_load=extensions_to_load)
 
     # Initialize fields so that an explosion during init doesn't break in Close.
-    self._browser_type = browser_type
     self._cri = cri
     self._is_guest = is_guest
     self._forwarder = None