[moblab] Uprev the stable base image to R66

TEST=None
BUG=chromium:838612

Change-Id: I5eef8a367e8ee05f3513a4eb798a48afb1477364
Reviewed-on: https://chromium-review.googlesource.com/1037625
Reviewed-by: Keith Haddow <haddowk@chromium.org>
Commit-Queue: Keith Haddow <haddowk@chromium.org>
Tested-by: Keith Haddow <haddowk@chromium.org>
diff --git a/moblab_config.ini b/moblab_config.ini
index 9fabea3..048f82c 100644
--- a/moblab_config.ini
+++ b/moblab_config.ini
@@ -35,7 +35,7 @@
 cts_results_server:
 # In moblab, this paramater is empty and uses the image bucket by default.
 results_storage_server:
-stable_cros_version: R64-10176.72.0
+stable_cros_version: R66-10452.74.0
 
 # The pubsub topic the gs_offloader notification is sent to.
 cloud_notification_topic: projects/chromeos-partner-moblab/topics/moblab-notification