Google is currently in the process of updating the API used by Chrome extensions. This wasn't something that the average user was particularly concerned about, until extension developers pointed out that one of the proposed changes could prevent many ad blockers (including uBlock Origin) from working. While Google hasn't completely abandoned its plans, it has made concessions in the wake of the public outcry and legal threats it has received.
The current Chrome extensions API, called Manifest V2, was introduced in 2012. Since then, Chrome has been the victim of malicious extensions many times. With Manifest V3, which is currently in development, Google hopes to reduce the potential damage that malicious extensions could do, while increasing performance and adding new features.
One of the proposed changes is a new declarativeNetRequest API, which is designed to replace the webRequest API that many extensions (including AdBlock Plus and uBlock Origin) use. Simply put, instead of extensions doing the network filtering themselves, they will provide a list of filters that Chrome will parse.
It stands to reason that sending every network request to an extension and having the browser pause until the extension sends a response will slow down its performance. Cliqz, the company behind the popular Ghostery browser extension, decided to conduct a study on the effects of ad blockers, and the results don't match what Google has stated.
The study conducted by Cliqz showed that the average performance impact on popular ad blockers – including Ghostery, uBlock Origin and AdBlock Plus – was often less than 0.05 milliseconds. While the design document stated that the existing API could only slow down Chrome, in practice, it’s not something the average user would notice.
Cliqz has previously expressed its disappointment with the proposed API changes. In a post, the company wrote: “They pretend to do this for privacy and browser protection reasons, but in reality, users will be left with very limited ways to prevent third parties from tracking their online activity or blocking unwanted content. Is Google doing this to protect its advertising business or simply to impose its own rules on everyone else? This is nothing less than another case of abusing its market position. If this is the case, we will file a complaint.”
In response to the outcry from developers and users, Chrome engineer Devlin Cronin wrote that new features are being added to the replacement API and defended the company, saying that all changes are still under discussion.
It also describes changes made to the proposal based on developer feedback. In short, the old API will eventually stop being able to block network requests, but Google has relaxed some of the restrictions for the new API.
