Mozilla is beginning to make a series of changes to Firefox that'll make certain aspects of the browser operate a lot more like Chrome. The changes are broadly designed to make Firefox more secure and stable, but they also have the downside of making it less customizable and potentially more of a resource hog.
"Developers who already support Chrome extensions will benefit."
There are a few key changes that Mozilla is making to get there. The first is that it's changing how extensions (which Firefox calls "add-ons") connect to the browser. Mozilla is beginning to require that they use a new method that's very similar to what's used by Chrome and Opera. While that means Firefox extensions may need to be rebuilt, it'll mean that Chrome and Opera extensions should be able to add Firefox support with minimal changes. "Developers who already support Chrome extensions will benefit since they will have one codebase to support instead of two," Mozilla writes in a blog post.
Mozilla is also beginning to require that all extensions go through a security check before they can be installed (currently, only extensions that are submitted to Mozilla's official add-ons gallery go through these checks). While there will be some way to get around this — mostly for developers — this means that every extension that the average person installs will have to pass through Mozilla. For the most part, that's going to be a good thing. "Extensions that change the homepage and search settings without user consent have become very common, just like extensions that inject advertisements into web pages or even inject malicious scripts into social media sites," Mozilla wrote earlier this year. There are obviously some huge security issues in letting extensions run through a web browser unchecked, and Mozilla is beginning to change that.
Mozilla is trying to make Firefox more stable and secure
The other updates relate to changing technologies inside of Firefox itself. For one, Firefox's behind-the-scenes tab management is soon going to work a lot more like the way Chrome handles tabs. Rather than running the browser and web content all together, Chrome splits them up so that the browser frame is separate from each individual browsing tab. It means that if one tab crashes, everything else can keep moving just fine, rather than the entire browser going down with it. There are also some security enhancements that come with tabs being kept independent of each other. This is essentially the model that Firefox is moving over to. At first, Mozilla will simply be separating the browser and the web content into two items, but over time it sounds like the plan is to break apart each tab. That might lead to some of the resource issues that Chrome has, but there's a good argument to be made that it's a fair trade-off for stability and security.
Finally, Mozilla is changing some of the underlying technology that it uses to build Firefox. That result is that extension developers aren't going to be able to alter the browser in quite as deep of a way. That's going to be a disappointment for some, but it's certainly not a reason for immediate outrage: Firefox has long been far more customizable than other browsers, but it was customizable in a way that could pose security and stability issues. Currently, "add-ons have complete access to Firefox’s internal implementation" of core technologies, Mozilla writes. That's apparently also led to development slow downs, which Mozilla hopes to avoid by changing what extensions are capable of.
These changes are going to be rolling out over the next year or so, with some starting much sooner. Extensions are going to have to be approved starting with Firefox 42, which comes two versions from now. Firefox 43 is supposed to begin separating the browser itself from the content inside its tabs; the deeper changes will come about around 12 to 18 months from now. It's likely that that's when developers will have to switch over to the new method of making extensions.