[autotest] Add the 'continuous' pool to lab inventory management.

We're creating a new pool named 'continuous' that will be used by
certain continuous Chrome builders in order to improve the gardening
process.  Those pools will be treated the same as the 'bvt' and 'cq'
pools for inventory management purposes.

BUG=chromium:569743
TEST=None

Change-Id: I2f056d32d80a2d5d739cf7a59a156a4e40fa7ed0
Reviewed-on: https://chromium-review.googlesource.com/317985
Commit-Ready: Richard Barnette <jrbarnette@chromium.org>
Tested-by: Richard Barnette <jrbarnette@chromium.org>
Reviewed-by: Fang Deng <fdeng@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
diff --git a/site_utils/lab_inventory.py b/site_utils/lab_inventory.py
index 965817b..7c1ad32 100755
--- a/site_utils/lab_inventory.py
+++ b/site_utils/lab_inventory.py
@@ -84,7 +84,7 @@
 # _MANAGED_POOLS - The set of all the general purpose pools
 #     monitored by this script.
 
-_CRITICAL_POOLS = ['bvt', 'cq']
+_CRITICAL_POOLS = ['bvt', 'cq', 'continuous']
 _SPARE_POOL = 'suites'
 _MANAGED_POOLS = _CRITICAL_POOLS + [_SPARE_POOL]