Whenever I look in Chrome's console, I see this error message:
Site cannot be installed: the page is not served from a secure origin
This only started happening a few days ago, and Chrome wasn't updated in the meantime.
This error is caused by sites served over HTTP if "Add to shelf" is enabled in chrome://flags.
Solutiuon: go to chrome://flags/#enable-add-to-shelf and change "Enabled" to "Default", then relaunch chrome.
来源：https://stackoverflow.com/questions/41863050/why-does-chrome-keep-displaying-site-cannot-be-installed-the-page-is-not-serve