How do these chips appear?
It is hard to understand how a crack or chip can be repaired without knowing and understanding how auto glass is built. In the automotive industry two types of glass are used: laminated glass , used at the windshields and secure glass used at the side and rear windows. Laminated glass has two layers of glass and between these two layer there is another layer, a film called poli-vinil-butiral, all pressed together like a sandwich.
When an object hits the windshield with high speed, the exterior layer of the laminated glass cracks, but thanks to the vinil which absorbs most of the impact . Otherwise this impact would shatter the glass, but this way it is limited and localized. Usually a the chip has a round or star shape with a diameter between 5 and 25 mm. The chip on the glass is in fact a cavity filled with air, created by the shockwave of the impact.