You’re also going to start seeing an option to “stream” some apps you don’t have installed, right from Google Search, provided you’re on good Wifi. For example, with one tap on a “Stream” button next to the HotelTonight app result, you’ll get a streamed version of the app, so that you can quickly and easily find what you need, and even complete a booking, just as if you were in the app itself. And if you like what you see, installing it is just a click away. This uses a new cloud-based technology that we’re currently experimenting with.
Source : Inside Search: New ways to find (and stream) app content in Google Search