Have determine_chrome_version use a build_target to match controller call.

BUG=chromium:1015064
TEST=manual, run_tests

Change-Id: Ic6c98ff129441ffe2bf6c289633041bfa9e6ee05
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1865528
Reviewed-by: Alex Klein <saklein@chromium.org>
Tested-by: Michael Mortensen <mmortensen@google.com>
Commit-Queue: Michael Mortensen <mmortensen@google.com>
diff --git a/service/packages_unittest.py b/service/packages_unittest.py
index 0d1b7be..425df19 100644
--- a/service/packages_unittest.py
+++ b/service/packages_unittest.py
@@ -135,7 +135,7 @@
 class ChromeVersionsTest(cros_test_lib.MockTestCase):
   """Tests getting chrome version."""
   def setUp(self):
-    self.board = 'board'
+    self.build_target = build_target_util.BuildTarget('board')
 
   def test_determine_chrome_version(self):
     # Mock PortageqBestVisible to return a valid chrome version string.
@@ -144,7 +144,7 @@
     self.PatchObject(portage_util, 'PortageqBestVisible',
                      return_value=r1_cpv)
 
-    chrome_version = packages.determine_chrome_version(self.board)
+    chrome_version = packages.determine_chrome_version(self.build_target)
     version_numbers = chrome_version.split('.')
     self.assertEqual(len(version_numbers), 4)
     self.assertEqual(int(version_numbers[0]), 78)