Samsung is pretty big. I mean really big. They have been contracted to build processors for Apple devices and in fact make their own processors for TVs, mobile phones, tablets and Chromebooks. After some issues with the Snapdragon 810 and over-heating (at the very least running really, really hot) issues, Qualcomm has opted to go with Samsung as the semiconductor manufacturer for the Snapdragon 820. It's interesting that they had to talk to the competition to build a chip for them. I'm sure Samsung is making a fair bit of money by agreeing to make the competitor's product.
The giant processor company has traditionally employed Taiwan Semiconductor (TSMC) to manufacture its chips, which power a large number of our smartphones and tablets. However, according to a report from Re/code, Qualcomm will be switching suppliers and partnering with Samsung for its next batch of high-end SOCs.