Pass a Chrome object to post_processing_after_browser.

https://chromium-review.googlesource.com/#/c/351590/ changed it to take
arc_mode instead of self, but the callee expects a Chrome object.

TEST=Autotest on cheets.
BUG=None

Change-Id: I611542579e76d1b64a7610e8ec396d9832b9715b
Reviewed-on: https://chromium-review.googlesource.com/352290
Reviewed-by: Luis Hector Chavez <lhchavez@google.com>
Commit-Queue: Ricky Zhou <rickyz@chromium.org>
Trybot-Ready: Ricky Zhou <rickyz@chromium.org>
Tested-by: Ricky Zhou <rickyz@chromium.org>
diff --git a/client/common_lib/cros/chrome.py b/client/common_lib/cros/chrome.py
index b6a3f34..a9bd453 100644
--- a/client/common_lib/cros/chrome.py
+++ b/client/common_lib/cros/chrome.py
@@ -193,7 +193,7 @@
                 if _is_arc_available():
                     if not disable_arc_opt_in:
                         arc_util.opt_in(self.browser)
-                    arc_util.post_processing_after_browser(arc_mode)
+                    arc_util.post_processing_after_browser(self)
                 break
             except (exceptions.LoginException) as e:
                 logging.error('Timed out logging in, tries=%d, error=%s',