UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36

Steps to reproduce the problem:
1. Load an extension that configures `chrome.proxy.settings` via the `ChromeOptions.addExtensions` API.
2. Exit Chrome.
3. Open Chrome normally.

What is the expected behavior?
The extension is no longer installed after restarting Chrome so the proxy settings should revert to what they were before (not configured or configured by some other extension that is still installed).

What went wrong?
The proxy settings remain set and are unavailable to be controlled by another extension (settings API returns `controlled_by_other_extensions`).

Did this work before? N/A 

Chrome version: 60.0.3112.113  Channel: stable
OS Version: 7.0
Flash Version: 

I can provide source code for the extension if required, this should work with any extension configuring proxy settings though.