I'm quite certain Apple would have continued their browser engineering and security efforts with or without Google. In the first place, Chromium was a fork of WebKit (which itself is derived from the work of the KHTML team). Apple values the security of their iOS users a lot so they wouldn't have just sat around and watched them get exploited.

It's true that Google 'got there first' on a lot of stuff and that groups like Project Zero do incredible work but the idea that we'd be nowhere without Google is a bit silly.