When does chrome.devtools.network.onRequestFinished.addListener(callback) fire?

Question

Google Chrome

Hello!
Can you please tell me when chrome.devtools.network.onRequestFinished.addListener(function callback) fires. I was expecting that one to fire after every request is completed. That is, like chrome.webRequest.onCompleted.addListener(function callback). However, I have noticed that it works when I update an extension in browser://extensions/ for example.

manifest.json:

{
  "name": "Orion-X",
  "version": "0.1",
  "manifest_version": 2,
  "minimum_chrome_version": "19",
  "description": "Eclipse Orion Chrome DevTools Extension",
  "icons": {
     "16": "/img/orion16.png",
     "24": "/img/orion24.png",
     "128": "/img/orion128.png"
  },
  "page_action": {
    "default_icon": "/img/orion16.png",
    "default_title": "Orion-X"
   },

  "devtools_page": "devtools.html",
  "permissions" :
    [
      "http://*/*",
      "https://*/*",
      "tabs",
      "contextMenus",
      "webNavigation",
      "webRequest",
      "debugger",
      "webRequestBlocking"
    ],
  "background": {
    "scripts": ["background.js"]
  }
}