There are many Freeware tools, Security Programs or add-on out there which silently adds extensions in your browser during their installation, without asking your permission. Though most likely you won’t face an issue but still it posses a high security risk especially if somehow you ended up installing a malicious tool.
Taking a note of this, Google have decided to give more control to user on this behavior. On Friday, “Google announced that as of Chrome 25, Silent extension deployment options on Windows will be disabled by default and each of the previously installed extensions using this method will automatically get disabled.”
Silent extension installation was originally designed for the Software companies and developers – it allows them to use the Windows registry to install a Chrome extension along with the installation of their software.
This feature have been widely abused by “third party Tools” which install their own extension without the knowledge of the user. But with the release of Chrome 25 this will be no longer possible. Chrome will inform you about the extension trying to install itself and provides you a options to enable the extension or remove it from your browser.
If for some reason you weren’t able to decide what to do with the extension at the time of appearance of notification. You will still have the option to manually Enable or remove the extension from the Chrome extension manager, until than it will be disabled by default.
Right now this feature is available in dev build of chrome and will take some time before the feature will be added to stable version of Google Chrome.
Overall, this is a welcome feature for Chrome user and an important security upgrade as it increases the level of browser security and provides more control to the user.