That obnoxious spinner is used for Mr. Tinkles, the Asshole Of Notification. Because even after Mr. Tinkles starts ringing out, he has no idea what to say. So when you click on him to make him shut the hell up, he still hasn't loaded the hundred bytes of your notification, and you have to look at that stupid spinner while all of Google's horrifying social storage infrastructure lurches into action. And because Mr. Tinkles is part of Google's all-in Social Death Pact, you have to load that image on every Google property: Gmail, Maps, Drive, Search, everything.