Update porting-a-google-chrome-extension.md (#1899)

src/content/documentation/develop/porting-a-google-chrome-extension.md

@@ -41,7 +41,7 @@ date: 2019-05-19 11:54:36
 
 The browser extension APIs are designed to promote cross-browser compatibility among extensions. The WebExtension APIs is therefore, to a large extent, code-compatible with the [extension API](https://developer.chrome.com/extensions) supported by Google Chrome and Opera. Extensions written for these browsers will, in most cases, run in Firefox with just a few changes. Almost all of the [WebExtension APIs](https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API) provide support for callback functions under the `chrome` namespace, the same as Chrome. The only APIs that aren't supported in the `chrome` namespace are those that are intentionally incompatible with Chrome. In those cases, the API documentation page states that support is provided only in the `browser` namespace. The process of porting an extension from Chrome or Opera is, therefore, relatively straightforward:
 
-1. Review your use of `manifest.json` features and Chrome extension APIs against the [Chrome incompatibilities reference](https://developer.mozilla.org/Add-ons/WebExtensions/Chrome_incompatibilities). Mozilla provides a service that can help to automate this step: [extensiontest.com](https://www.extensiontest.com/). If you're using features or APIs that aren't supported in Firefox, you might not be able to port your extension.
+1. Review your use of `manifest.json` features and Chrome extension APIs against the [Chrome incompatibilities reference](https://developer.mozilla.org/Add-ons/WebExtensions/Chrome_incompatibilities). Mozilla provides a service that can help to automate this step within the [Add-on Developer Hub](https://addons.mozilla.org/developers/addon/validate). If you're using features or APIs that aren't supported in Firefox, you might not be able to port your extension.
 2. Install your extension in Firefox by using [`about:debugging`](https://developer.mozilla.org/docs/Tools/about:debugging) or the [web-ext tool](/documentation/develop/getting-started-with-web-ext#testing-out-an-extension) (similar to Chrome’s command-line tools).
 3. [Test your extension](/documentation/develop/debugging).
 4. If you have any problems, contact us on the [dev-addons mailing list](https://mail.mozilla.org/listinfo/dev-addons) or [Add-ons](https://mzl.la/2u8ZGbg) channel on [Matrix](https://wiki.mozilla.org/Matrix).