chromeos: convert remaining AshTest usage to AshTestBase

ash/test/BUILD.gn

Index: ash/test/BUILD.gn
diff --git a/ash/test/BUILD.gn b/ash/test/BUILD.gn
index e01193960b3d5723274c9034bb7dcfb0e0b073d0..d7ad07b1da29919216971417053bc306c7780bd7 100644
--- a/ash/test/BUILD.gn
+++ b/ash/test/BUILD.gn
@@ -54,26 +54,15 @@ static_library("test_support_common") {
     "../laser/laser_pointer_controller_test_api.h",
     "../laser/laser_pointer_points_test_api.cc",
     "../laser/laser_pointer_points_test_api.h",
-    "../mus/test/ash_test_impl_mus.cc",
-    "../mus/test/ash_test_impl_mus.h",
-    "../mus/test/wm_test_base.cc",
-    "../mus/test/wm_test_base.h",
-    "../mus/test/wm_test_helper.cc",
-    "../mus/test/wm_test_helper.h",
     "../rotator/test/screen_rotation_animator_test_api.cc",
     "../rotator/test/screen_rotation_animator_test_api.h",
     "../shell/toplevel_window.cc",
     "../shell/toplevel_window.h",
-    "ash_test.cc",
-    "ash_test.h",
     "ash_test_base.cc",
     "ash_test_base.h",
     "ash_test_environment.h",
     "ash_test_helper.cc",
     "ash_test_helper.h",
-    "ash_test_impl.h",
-    "ash_test_impl_aura.cc",
-    "ash_test_impl_aura.h",
     "ash_test_views_delegate.cc",
     "ash_test_views_delegate.h",
     "child_modal_window.cc",