Google uses a monolithic source code repository, so all of the source code is presumably still present within that repository. However, there is probably nothing that they can feasibly sell, as that source code is dependent on other parts of the Google infrastructure that are all part of that repository. It would probably be just as much work to extricate it from all of those entanglements as it would be to rewrite the product from scratch. Indeed, you could just go get an open–source product like NewsBlur for free and use that instead.