Google is working on a pair of new features for Chrome that will enable it to be a facilitator for devices and content, much like Google Cast and Chromecast. Meet “Media Router & Web Presentation API”
“The media router is a component in Chrome responsible for matching clients that wish to render content outside the browser (media sources) with devices and endpoints capable of rendering that content (media sinks).“
It will be easier to understand this concept if you consider how Chromecast works. There is a media source that supports casting, say Youtube. And then there is a device, your Chromecast that is capable of rendering that content.
Media Router on Chrome wants to expand this possibility beyond what we have now. Mirroring locally rendered content to external screens, including on-screen and off-screen tabs, Chrome apps windows, and the system desktop as François Beaufort says.
Web Presentation API
The Web Presentation API is the other side of the set up, enabling developers to set this up on their content or server. “The Web Presentation API allows a Web application to request display of Web content on a secondary (wired, or wireless) screen. The content may be rendered locally and streamed to the display or rendered remotely. The Web application controls the content by two-way messaging.”
These two sound very interesting to me. If you are a developer, you must check this out too. Find more details here and here.