UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36

Steps to reproduce the problem:
1. 
Create an extension that requests the "background" permission, and also registers a listener for chrome.runtime.onUpdateAvailable:

chrome.runtime.onUpdateAvailable.addListener(() => undefined })

2. 

Publish the extension on the webstore.

3. 

Update the extension version and publish to webstore.

4.

Go to chrome://extensions

5.

Click "Update now". Observe that the extension behaves as though chrome.runtime.reload() is called, instead of waiting for the browser to restart to reload the extension.

What is the expected behavior?
The expected behaviour is that when an extension registers a listener for onUpdateAvailable, and explicitly _does not_ call chrome.runtime.reload(), that the extension will not be reloaded until the browser restarts.

What went wrong?
The extension is reloaded, ignoring onUpdateAvailable being registered and returning 'undefined' and explicitly not calling chrome.runtime.reload().

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 62.0.3202.94  Channel: n/a
OS Version: OS X 10.11.6
Flash Version: 

This causes a critical bug in my extension, where a user is logged out on extension update instead of waiting for the browser to be restarted.