When I saw it I was wondering too. However I checked mine and it looks similar. I have been playing music from google play music from the speakers for roughly 5 hours....it isn't even on the battery graph . Been browsing for about 2 hours too and chorme barely shows up.
Google should implement better stats than what is currently shown. Apps like BetterBatteryStats show more details, but I would prefer a native built in stat indicator similar to BetterBatteryStats.