Google announced the change of its official logo on its official blog on Tuesday.
https://g.co/doodle/mqh2ny
It said that the logo, and its many variations, would work better on the many different-sized screens through which people used or encountered Google and its services. As well as the full logo of the company’s name, it also plans to use four dots in its signature blue, red, yellow and green colors and a single, multi-colored capital “G” to represent it.
Observe Google’s evolution :
Google justifies the need for change with the response of ‘Google usage from various devices’.
Get More details from its BLOG