Fix wording to comply with respectful-code

https://source.android.com/setup/contribute/respectful-code

Test: Run unit tests
Change-Id: Ia6647c9cf3224b962286151932118093b9ad979a
diff --git a/payload_state_unittest.cc b/payload_state_unittest.cc
index bf9aed4..d8d9afa 100644
--- a/payload_state_unittest.cc
+++ b/payload_state_unittest.cc
@@ -1016,7 +1016,7 @@
   NiceMock<MockPrefs>* mock_powerwash_safe_prefs =
       fake_system_state.mock_powerwash_safe_prefs();
 
-  // Mock out the os version and make sure it's blacklisted correctly.
+  // Mock out the os version and make sure it's blocklisted correctly.
   string rollback_version = "2345.0.0";
   OmahaRequestParams params(&fake_system_state);
   params.Init(rollback_version, "", false);