Add parrot to the HWTest try-bots.

cbuildbot --remote --hwtest now works with parrot.

BUG=chromium:253593
TEST=Kicked off Parrot HWTests.

Change-Id: Ic2041657c3538c53023e0b810188662015d5a78a
Reviewed-on: https://gerrit.chromium.org/gerrit/59818
Tested-by: Prashanth Balasubramanian <beeps@chromium.org>
Reviewed-by: Alex Miller <milleral@chromium.org>
Commit-Queue: Prashanth Balasubramanian <beeps@chromium.org>
diff --git a/buildbot/constants.py b/buildbot/constants.py
index 652c38d..e536d05 100644
--- a/buildbot/constants.py
+++ b/buildbot/constants.py
@@ -217,7 +217,7 @@
 HWTEST_CHROME_PERF_POOL = 'chromeperf'
 HWTEST_TRYBOT_POOL = 'try-bot'
 # Currently supported hwtest boards.
-HWTEST_BOARD_WHITELIST = ['x86-mario', 'lumpy', 'daisy']
+HWTEST_BOARD_WHITELIST = ['x86-mario', 'lumpy', 'daisy', 'parrot']
 HWTEST_AU_SUITE = 'au'
 
 # Defines VM Test types.