Don't act all snarky when someone says the only way not to be tracked is to not carry a phone. It's pretty close to being true, and you don't know if hitting the software switch to turn off your GPS really turns it off or if it goes into a low power mode where it only updates your position every five minutes- this is not unheard of to keep the time to fix low for when a person turns location services back on.
As mentioned in the article, Google was previously caught tracking people even when they had location, data, and Wi-Fi turned off. We just have to take their word now that they don't do it anymore, and the word of a big profit driven corporation that has been implicated in PRISM and previously tracked people isn't worth too much.
Furthermore, even if Google doesn't track you the cell phone companies still know which tower your cell phone was connected to, so they know your location within three miles at all times. It's not as precise as GPS info, but the police could still ask the cell phone companies to give them a list of phone accounts that were visible to a specific set of cell phone towers at a particular set of times.