Google built a little application that downloaded and installed Chrome, and the company submitted that application to the Microsoft Store. Because the Microsoft Store actually imposes minimal verification or validation of submitted applications, Microsoft's automated processes duly published the app. It was available for a few hours. Then Microsoft took notice of the installer and yanked it from the Store.
This is a sequence of events that's bad for both companies.
Google wrote its installer app to provide a safe way to install Chrome. Throughout its life, Microsoft's app store has been plagued with crap applications. Apps that leverage the branding and trademarks of other companies, purporting to be one thing but actually being another, have been endemic in the Store; even today, you can find apps that masquerade as Chrome or try to use Chrome's name and logos to separate people from their money.