If think of it then there be no competition any more even by a little. If Google Decide to give up on chrome and make there own close Source web engine. Nothing really stopping them as they control the web and search even taking then to count not going make them support the chrome web engine. Firefox just uphill battle even more now as user can't give up ther chrome habits and the forks.
They don't need a brand new closed source browser, chrome is already closed source.
Sure, a lot of the heavy lifting is done inside the open source chromium's code , but all the things that turns a profit for Google is the closed source additions (a million kinds of telemetry) .