I don't think it's an advance towards a police state, it's nothing new at all. The police have always used violence against those who disobey them, or those who attend demonstrations deemed politically unacceptable (irrespective of the disruption or threat posed). What has changed in the last couple of years is the prevalence of pocket devices with video capacity.
This is not in any way to diminish the rightful anger and disgust we feel at this, it's just to point out that we should be feeling it a lot more often.
The Guardian have footage of one of the protesters being sprayed. Police guidelines are clear that the spray should not be used from less than a metre "unless the nature of the risk to the officer is such that this cannot be avoided". The cop in the video sprays someone standing still and speaking.