Google’s latest version of the Chrome web browser offers an even more secure, tightly sandboxed version of the browser’s Flash Player plugin.

If you haven’t already updated you can download Chrome 21 from Google. Existing users may need to restart their browser for any updates to apply.

At the moment the Flash Player improvements are only available to Windows users, but the change does apply to the entire Windows spectrum, covering everything from Windows XP (where Chrome is the only option if you want to keep Flash sandboxed) to the coming Windows 8.

As Chrome Software Engineer Justin Schuh writes on the Chromium blog, “Windows Flash is now inside a sandbox that’s as strong as Chrome’s native sandbox, and dramatically more robust than anything else available.”

The Flash update sees Chrome dropping the older Netscape Plugin API — which browsers have long relied on for plugin security — in favor of Google’s own Pepper Plugin API (PPAPI). Since PPAPI has a tighter sandbox it makes it harder to exploit Flash, but Schuh says the new architecture will make Flash more stable as well. “By eliminating the complexity and legacy code associated with NPAPI, we’ve reduced Flash crashes by about 20%.”

There are also performance gains since the PPAPI offloads some of the display work to your PC’s GPU, which makes for faster rendering and smooth scrolling. The new Pepper API also means Flash will work in Windows 8′s don’t-call-it-Metro mode.

Google says that it’s working on bring the same Pepper-based sandboxing to Chrome for Mac OS X and hopes to “ship it soon” (Linux users have enjoyed PPAPI-based Flash Player since Chrome 20).

Head to Sketchbots with Chrome 21 and your image will soon appear in the sand. Image: Google

What if web apps could see? What if they could hear?

That’s the far-fetched opening to Google’s latest Chrome update announcement. But as it turns out, it’s not all that far-fetched. In fact Chrome 21, which is now available in the stable channel, can, like coming versions of Firefox and Opera, use your webcam to see and your microphone to listen.

The magic behind Chrome 21′s all-seeing gaze is the getUserMedia JavaScript API, which gives developers access to your webcam and microphone. The getUserMedia API is part of WebRTC, a larger group of proposed standards that will eventually make web apps capable of many of the same feats that currently require platform-native APIs.

Whenever you point Chrome 21 to a web app that wants to access your camera or microphone, Chrome will display a prompt requesting permission, and, assuming you allow it, you’ll also get the option to select which device to use — i.e., a USB headset instead of a built-in mic.

If you’d like to see it in action Google has an impressive new demo to show off Chrome’s getUserMedia capabilities. Sketchbots is an experiment that uses getUserMedia to grab a picture of your face via webcam and then converts the image to a line drawing. The line drawing is then sent to a robot in the Science Museum in London where the robot draws out your portrait in a patch of sand, which you can watch live on YouTube (and is seen by anyone visiting the museum).

Chrome 21 also adds official support for Apple’s new high-res Retina Macbook Pros. This release also introduces support for the Gamepad JavaScript API, which will allow developers to write web-based games that use videogame controllers.

Coming soon to Windows 8 Preview: Google Chrome. Illustration: Webmonkey

Google is hard at work on a version of its Chrome browser that will work with Windows 8′s Metro environment. The Chromium blog recently announced that the next build of Chrome’s dev channel will run in both the Metro and desktop environments of Windows 8.

If you’d like to try it out a version of Chrome on Windows 8 once it’s available — most likely later today or perhaps over the weekend — you’ll need to switch over to the Chrome dev channel.

While Chrome will run in Windows 8′s Metro interface on desktop PCs, Google faces the same Microsoft platform restrictions Mozilla has spoken out against and as of now there will be no version of Chrome for WinRT, the version of Windows 8 designed to run on ARM processors.

Since WinRT is the most likely candidate for tablets that means any Windows 8 tablets will be Chrome-free.

Google has stopped short of being as vocal as Mozilla — which has called WinRT “a return to the digital dark ages. The Chromium blog merely notes that “Microsoft is not allowing browsers other than Internet Explorer on the platform,” though there is a link in that sentence to Mozilla’s original post decrying Microsoft’s restrictions.

The crux of Mozilla’s gripe — which Google seems to be tacitly endorsing as well — is that in Windows RT Microsoft gives its own Internet Explorer access to special APIs other web browsers can’t use.

Mozilla’s Asa Dotzler has previously pointed out that at least part of what makes this different than Apple’s iOS — which imposes similar restrictions on software — is that Microsoft still has binding agreements with the EU about browser choice on Windows, and Windows RT is still Windows.

It’s possible that Microsoft will change its mind about third-party web browsers on WinRT (or be legally compelled to change its mind) before any Windows 8 tablets arrive, but in the mean time at least you’ll soon be able to use Chrome with Windows 8 on desktop machines.