Pretty sure he's talking about the original chat embedded in the Gmail interface. The earliest records I can find in my logs are from February 2006. For at least 7 years I used it, and for many years my usage was quite extensive. Either due to changed preferences when I got older or iMessage or other things, it looks like I generally stopped chatting in there around May 2013. From my perspective, Google was sitting on a gold mine because so many people I knew in the USA and across the ocean were using it and it worked very well until they started fiddling with the product in ways that made it more clunky.