If you are talking about the chrome to the rubber, you can just add some CS. The rubber shouldn't need anything to hold it against the glass. Actually, my chrome is tight enough to keep the rubber clamped against the glass. No sealant used.
Your talking the drivers and passengers window trim and weatherstrip? If the entire thing fell off the glass, yes, just silicone it back on the glass. If the part that attaches to the glass is still on the glass, and the part that holds the rubber weatherstrip is what came off, there really is no fixing that.
If it fell off intact, you can glue it back on. Silicone probably won't hold, though. Not strong enough. Use something made for the job, like 3M Channel Bonding and Sidelite Adhesive Part Number 08641.