According to Google, the company is now allowing developers to make use of the company's Google Cloud Messaging for Chrome feature throughout all Chrome channels – a long and convoluted way to say that Google is finally unlocking push notifications within Chrome OS and its Chrome browser.
Naturally, a user has to be signed into Chrome in order to make use of the feature, but Google's switch will allow apps and extensions to now push messages directly to users when particular actions occur. To borrow an example from Google's post in the Chromium Blog about the change, this could include actions like, "a news alert, a message sent to a user or a stock hitting a price threshold."
Previously, apps and extensions had to continuously query servers in order to determine whether a notification needed to be sent to a user – a process that, "consumed bandwidth and reduced the battery life of your users' machines," in the words of Google product manager Mark Scott.
The process is a bit easier now – and more of a real-time process, to boot. After a user installs a particular app or extension, said user's channel ID (a special identifier that distinguishes an app or extension's users from each other) gets passed along to the developer's server. When it comes time to send out a message, the server notifies Google Cloud Messaging which, in turn, fires off a message to "all instances of Chrome where the user is signed in," Google describes.
From there, Chrome notifies the particular app or extension of the incoming news (waking it up in the process, if said app or extension isn't actually running at the time the data comes in). The app or extension then performs a related action depending on whatever that data happens to be. In some cases, perhaps the app or extension fires up a particular web page; in others, perhaps a little notification box pops up in the corner of your browser to let you know about a particular event.
If you're a developer and the process sounds rather familiar, it's because it's analogous to the longstanding Google Cloud Messaging for Android service — the mobile equivalent of Chrome's push system.