Chaos over, Internet Download Manager developer team seems to have finally hosted their extension, IDM Integration Module in Chrome Web Store. So you no longer need to use developer mode to install their extension in stable and beta channels.
Installing IDM Integration module in Chrome from Web Store
1. After installing IDM in your computer, visit this link in Chrome browser.
2. Click ‘Free’ and click on ‘Add’ button to install it.
If you don’t know: Google has made their policy tougher which means the Chrome browser strictly won’t allow extension installs outside Web Store, in case of stable channel Chrome 33, which soon to release, they’ve extended the deadline for hosting of extension in online Store till May 1, after that, if you’ve their extension installed from other sources, it will be disabled and can’t be enabled by user like before.
Note: From onwards, always install IDM extension from Chrome Web Store.