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

chrome/test/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
@@ skipping 3026 matching lines @@
     "../browser/resources/print_preview/data/measurement_system.js",
     "../browser/resources/print_preview/print_preview_utils.js",
     "../renderer/resources/extensions/notifications_custom_bindings.js",
     "../renderer/resources/extensions/notifications_test_util.js",
     "//ui/webui/resources/js/cr.js",
   ]
   if (is_chromeos) {
     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",
     ]
   }
 }
 
 test("unit_tests") {
   sources = [
     # histograms.xml is analyzed by AboutFlagsHistogramTest, so this
     # dependency is needed to make commit bots run unit_tests on
     # histograms.xml changes.
     "../../tools/metrics/histograms/histograms.xml",
@@ skipping 2127 matching lines @@
 }
 
 if (is_win) {
   loadable_module("conflicts_dll") {
     testonly = true
     sources = [
       "conflicts/conflicts_dll.cc",
     ]
   }
 }