why google implementing rounded-corner elements in UI of all products?

I have been observing this for some weeks. there are little to huge changes in UI in most of the Google's products(browser, google-search, fit, mobile-browser). What attracted me their's implementation of rounded-corner elements(talking HTML here). take the search icon, new tab button and where not.

I think most of you observed these changes. why this sudden shift in the design? why rounded-corner elements?