UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/53.0.2785.143 Chrome/53.0.2785.143 Safari/537.36

Steps to reproduce the problem:
The Chrome extension we've developed modifies certain HTTP headers in order for itself to function properly.

We've noticed that if another extension modifies the same HTTP header, then the user sees the following warning message:
"Warning:
This extension failed to modify the response header "content-security-policy" of a network request because the modification conflicted with another extension (HubSpot Sales)."

We would like our extension to be notified if this happens, but the current behavior in Chrome is that extensions only get notified for canceled requests, not modified ones.

Quoting from https://developer.chrome.com/extensions/webRequest (under the section "Conflict resolution"):
"In the current implementation of the web request API, a request is considered as cancelled if at least one extension instructs to cancel the request. If an extension cancels a request, all extensions are notified by an onErrorOccurred event. Only one extension is allowed to redirect a request or modify a header at a time. If more than one extension attempts to modify the request, the most recently installed extension wins and all others are ignored. An extension is not notified if its instruction to modify or redirect has been ignored."

What is the expected behavior?
The extension is notified in some way that another extension is modifying the same HTTP header.

What went wrong?
The extension is NOT notified that another extension is modifying the same HTTP header.

Did this work before? No 

Does this work in other browsers? N/A

Chrome version: 53.0.2785.143  Channel: stable
OS Version: 
Flash Version: