The age of sideloading extensions is over for Chrome users on Windows PCs. After announcing Chrome would become a walled garden in November, Google followed through with its promise on Tuesday.

Chrome for Windows will no longer allow you to install browser extensions originating outside the Chrome Web Store. Any previously installed extensions you're using that didn't come from the Web Store may also be automatically disabled. If they are, you will not have the option to re-enable or re-install these extensions unless they enter the Chrome Web Store.

Developers and enterprise users will still be able to sideload apps on Chrome installations under their control. For most users, however, it's the Chrome Web Store or nothing.

Google says it is creating the new policy to protect users from malicious software.

"Malware can change how browsers work by silently installing extensions on your machine that do things like inject ads or track your browsing activity," Google said in a blog post announcing the policy enforcement. "If you notice strange ads, broken web pages or sluggish browsing after installing some new software or plugins, you could be affected."

Inline installs let you add extensions to Chrome without visiting Google's Web Store.

Despite the policy change, you may still see the option to install extensions that are seemingly outside Google's extension playground. The Evernote Clearly extension, for example, can be installed directly from Evernote's site. But the extension is actually coming from the Chrome Web Store thanks to a featured called inline installs.

The point of inline installs is to let users install extensions from the Chrome Web Store without leaving the site they're currently visiting.

It's hard to know how often people were sideloading Chrome extensions since almost everything you need can be found in the Chrome Web Store anyway. Nevertheless, it's a shame to see Google close down Chrome this way, considering how many years Google spent promoting the wonders of the open web.

But it appears the realities of dealing with Windows malware had become too difficult.

That's not all that's going on here, however. These days, Google is also using Chrome as something of an advertisement for Chrome OS. Features like stand-alone apps, the Windows and Mac versions of the Chrome App Launcher, offline support, and the Chrome OS-like interface hidden in Chrome's Metro app for Windows 8 are all designed to show off the power of going Google.

Combine the encroaching Chrome ecosystem with beefed up security for Chrome users, and who knows? Maybe a few more PC owners will be convinced to pick up a $300 Chromebook instead of a Windows 8.1 PC they next time they're roaming the aisles at Best Buy.