How Google puts unwanted apps on our Macs? I cannot find in my memory a situation when I was installing anything from Google except from Google Chrome (that is my main browser).

Recently I saw on my Mac an app titled Google Search.app. 



(Above screenshot taken from Launchpad)

Tiny (87 KB) but in my case definitely unwanted. I see that the only thing it does when opened is open Chrome with a new tab which has google.com for its url.

This makes no sense to me. Also this app is not stored in my home directory /Users/slick/Applications/Chrome Apps. Rather, it is stored in /Applications. Will definitely land into the Trash.

Question: How it was installed without my permission (if I'm a root on my own computer)? How should I stop this in future?
The "apps" come bundled with Chrome. These aren't actual apps, just links to Google services that are wrapped to look like a standard app (think of the as the OS equivalent of browser bookmarks to Google sites). You can safely delete them, but they will likely reappear should you re/install Chrome.