autotest: Initialize network backend conditionally.

No functional change in this CL, but we introduce the facility to
not initialize network backend. cheets_MediaPlayerVideoHWDecodeUsed
(in a diff repo), needs to be updated before we can default
init_network_controller to False.

BUG=chromium:681944
TEST=trybots.

Change-Id: Id4a6886fececc1a26478f24d0c9c67b563a00693
Reviewed-on: https://chromium-review.googlesource.com/431133
Commit-Ready: Achuith Bhandarkar <achuith@chromium.org>
Tested-by: Achuith Bhandarkar <achuith@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
diff --git a/client/common_lib/cros/chrome.py b/client/common_lib/cros/chrome.py
index 053e883..149f00f 100644
--- a/client/common_lib/cros/chrome.py
+++ b/client/common_lib/cros/chrome.py
@@ -79,7 +79,8 @@
                  disable_gaia_services=True, disable_default_apps = True,
                  auto_login=True, gaia_login=False,
                  username=None, password=None, gaia_id=None,
-                 arc_mode=None, disable_arc_opt_in=True):
+                 arc_mode=None, disable_arc_opt_in=True,
+                 init_network_controller=True):
         """
         Constructor of telemetry wrapper.
 
@@ -189,7 +190,8 @@
                               i, repr(e))
                 if i == num_tries-1:
                     raise
-        self._browser.platform.network_controller.InitializeIfNeeded()
+        if init_network_controller:
+          self._browser.platform.network_controller.InitializeIfNeeded()
 
     def __enter__(self):
         return self