Microsoft is pushing Bing heavily in its new operating system. Bing is the default search engine in Microsoft Edge, and while you can change this to Google (or any other choice), the process of doing so is far from intuitive -- you can’t simply pick "Google" from a list of options.
Cortana, Microsoft’s built-in personal assistant, is powered by Bing too, which means when you ask her a question she doesn’t immediately know the answer to, she’ll open up your default browser and display a list of results sourced from Microsoft’s search engine. There is a way to get her to use Google instead though, but you won’t find this in any Settings.
When Cortana performs a web search using Bing, the add-on will redirect the search to Google instead. It’s seamless and works very well. As a side note, the extension redirects all Bing searches in Chrome, not just Cortana ones.
Chrometana doesn’t only offer Google as a search choice. You can set it to use Yahoo or DuckDuckGo if you prefer.
This trick only works if you have Chrome set as your default web browser. Mozilla is working on its own implementation so future versions of Firefox will automatically redirect Cortana searches to your preferred search engine.