On Windows, Mac or Linux computers, run an antivirus or anti-malware software.On Windows computers, Check your computer for malware.If you repaired an extension but it's still corrupted, a suspicious program might be changing this extension's files. Next to 'Allow this extension to read and change all your data on websites that you visit', change the extension’s site access to On click, On specific sites or On all sites. Allow site access: On the extension, click Details.Fix corruptions: Find a corrupted extension and click Repair.Allow Incognito: On the extension, click Details.Turn on/off: Turn the extension on or off.At the top right, click More More tools Extensions.If the extension is trusted by Enhanced Safe Browsing, click Add extension to complete the installation.To abort the installation, click Close.To install the extension anyway, click Continue to install.

If the extension that you’re about to install isn’t trusted by Enhanced Safe Browsing, it says 'This extension is not trusted by Enhanced Safe Browsing'.When you try to install an extension, a dialogue appears.

Google chrome extension store