Why would Google replace its logo with a barcode? Probably because barcodes were invented 60 years ago. "This invention relates to the art of article classification and has particular relation to classification through the medium of identifying patterns. It is an object of the invention to provide automatic apparatus for classifying things according to photo-response to lines and/or colors which constitute classification instructions and which have been attached to, imprinted upon or caused to represent the things being classified," explains the patent.
To decode the doodle, upload the image to onlinebarcodereader.com and you'll notice that it uses Code 128 to encode "Google". There's also an online barcode generator.
It's not the first time when a doodle encrypted Google's name: Samuel Morse's birthday and Louis Braille's birthday were other opportunities for cleverly hiding Google's logo.