Added auto-scan, made some small changes to how prefs are stored, refactored.

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index 9cbcf4d5ecab848c47ebec2b35d355563ed4e169..3d9ad8595cbdb21af1fe306738533908d52afa16 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -3044,16 +3044,13 @@ js2gtest("unit_tests_js") {
     sources += [
       "../browser/resources/chromeos/braille_ime/braille_ime_unittest.gtestjs",
       "../browser/resources/chromeos/select_to_speak/select_to_speak_unittest.gtestjs",
-      "../browser/resources/chromeos/switch_access/switch_access_unittest.gtestjs",
+      "../browser/resources/chromeos/switch_access/tree_walker_unittest.gtestjs",
     ]
     extra_js_files += [
       "../browser/resources/chromeos/braille_ime/braille_ime.js",
       "../browser/resources/chromeos/select_to_speak/select_to_speak.js",
       "../browser/resources/chromeos/select_to_speak/test_support.js",
-      "../browser/resources/chromeos/switch_access/prefs.js",
-      "../browser/resources/chromeos/switch_access/switch_access.js",
-      "../browser/resources/chromeos/switch_access/test_support.js",
-      "../browser/resources/chromeos/switch_access/testable_switch_access.js",
+      "../browser/resources/chromeos/switch_access/tree_walker.js",
     ]
   }
 }