Google blocks sideloading of Chrome extensions

To protect users from malicious attacks, Google has implemented a change to the Chrome browser so that extensions can now only be installed if they are downloaded from the Chrome Web Store. For end users, this means that you cannot download an extension from another source and try to install or force the browser to run it. By going through the Chrome Web Store, Google is hopping that this will prevent malicious developers from releasing extensions that are harmful to unsuspecting Chrome users.

source: androidcentral