I cannot believe that some people online are asking why there are protests Chicago, since the officer has been arrested and charged with murder. Like that solves the problem and we should just move on.

The bubble is so thick.

Here's some problems that these protests are trying to highlight:

The Police fought the release of the tape showing the footage. If not for the repeated attempts by a reporter to have it made public, this police officer would still be on the force. He was on duty right up until the day the tape was released, and he was charged with murder. 

He likely would never have been charged if the tape was not ordered to be released.

There is over an hour of videotape missing. A local Burger King manager says that the police confiscated their camera/film which showed the shooting, and it went "missing" while in police custody.

The corruption is so thick that they may need to fire the whole force and start over. 

But asking why people are protesting? Give your heads a shake.