Google has a new logo, but it also has a new favicon. It's now a capital G that uses the four Google colors: blue, red, yellow and green.
Here's a screenshot that shows the old favicon launched in 2012 and the new one:
This is the new favicon, which is also used as an icon for Google Search:
You can find it in Google's app launcher and soon in Chrome's app launcher and in Android, as an icon for the Google Search app.