Fix "wpt update-expectations" for Chrome (#30487)

diff --git a/tools/wptrunner/wptrunner/browsers/chrome.py b/tools/wptrunner/wptrunner/browsers/chrome.py
index 0b6a0c6..5abccd1 100644
--- a/tools/wptrunner/wptrunner/browsers/chrome.py
+++ b/tools/wptrunner/wptrunner/browsers/chrome.py
@@ -24,6 +24,7 @@
                  "executor_kwargs": "executor_kwargs",
                  "env_extras": "env_extras",
                  "env_options": "env_options",
+                 "update_properties": "update_properties",
                  "timeout_multiplier": "get_timeout_multiplier",}
 
 def check_args(**kwargs):
@@ -129,6 +130,8 @@
 def env_options():
     return {"server_host": "127.0.0.1"}
 
+def update_properties():
+    return (["debug", "os", "processor"], {"os": ["version"], "processor": ["bits"]})
 
 class ChromeBrowser(Browser):
     """Chrome is backed by chromedriver, which is supplied through