brillo image: Different summary message for brillo tools.

Currently, both brillo image and cros image display the same summary message.
This CL changes it so brillo image displays a different summary message. It is
done by passing '--toolset=brillo' to build_image.

BUG=brillo:1189
TEST=unittests + manual tests
CQ-DEPEND=CL:275748, CL:275702, CL:275726

Change-Id: I62b75c6018177f53f96c647bd3dc07a968ae5c38
Reviewed-on: https://chromium-review.googlesource.com/275867
Reviewed-by: Steve Fung <stevefung@chromium.org>
Commit-Queue: Ralph Nathan <ralphnathan@chromium.org>
Trybot-Ready: Ralph Nathan <ralphnathan@chromium.org>
Tested-by: Ralph Nathan <ralphnathan@chromium.org>
diff --git a/cli/cros/cros_image_unittest.py b/cli/cros/cros_image_unittest.py
index dfa942b..1ab1a02 100644
--- a/cli/cros/cros_image_unittest.py
+++ b/cli/cros/cros_image_unittest.py
@@ -136,6 +136,16 @@
     self.assertEqual(1, op.call_count)
     self.assertTrue('--progress_bar' in op.call_args[0][1])
 
+  def testToolsetBrillo(self):
+    """Test RunCommand called with --toolset=brillo when using brillo."""
+    self.PatchObject(command, 'GetToolset', return_value='brillo')
+    self.SetupCommandMock([])
+    self.cmd_mock.inst.Run()
+
+    # Test that build_image is called with the correct arguments.
+    cmds = '\n'.join(repr(x) for x in self.rc_mock.call_args_list)
+    self.assertIn('--toolset=brillo', cmds)
+
 
 class ImageCommandParserTest(cros_test_lib.TestCase):
   """Test class for our ImageCommand's parser."""
diff --git a/lib/image_lib.py b/lib/image_lib.py
index 1f96b75..9b8cc61 100644
--- a/lib/image_lib.py
+++ b/lib/image_lib.py
@@ -341,6 +341,9 @@
   if image_types:
     cmd.extend(image_types)
 
+  if command.GetToolset() == 'brillo':
+    cmd.append('--toolset=brillo')
+
   if command.UseProgressBar():
     cmd.append('--progress_bar')
     op = BrilloImageOperation()