You're not the only one. So far, it's failing on both PC's running Win 7 64 Pro I've checked. It doesn't seem to have anything to do with Chrome's new version 53.0.02785.89, as both these PC's were running 52.0.2743.116 when it disappeared. They had a similar issue 3 months ago where the extension was disabling Google Calendar functions.
Please upgrade manually to your RingCentral for Google to 126.96.36.199 if Google has not pushed it automatically.
How to check the version - Type chrome://extensions/ in your browser address bar and look for "RingCentral for Google", If the version is showing lower than 188.8.131.52 , then click on the trash icon and allow to delete