[Android WebView] Add functionality to enable features and enable the spellcheck feature.

android_webview/test/BUILD.gn

Index: android_webview/test/BUILD.gn
diff --git a/android_webview/test/BUILD.gn b/android_webview/test/BUILD.gn
index 2db4c1963f4ab45e3fe12ad7c3459b8681b49f06..e998a375b7ac1235fc4f23bbbe5dca91c89d72e9 100644
--- a/android_webview/test/BUILD.gn
+++ b/android_webview/test/BUILD.gn
@@ -229,6 +229,7 @@ test("android_webview_unittests") {
     "../browser/aw_permission_manager_unittest.cc",
     "../browser/aw_static_cookie_policy_unittest.cc",
     "../browser/browser_view_renderer_unittest.cc",
+    "../browser/command_line_helper_unittest.cc",
     "../browser/net/android_stream_reader_url_request_job_unittest.cc",
     "../browser/net/aw_cookie_store_wrapper_unittest.cc",
     "../browser/net/input_stream_reader_unittest.cc",