Examine source code of Focused Browsing

{
  "name": "Focused Browsing",
  "version": "0.9.8",
  "manifest_version": 2,
  "description": "Reclaim your focus with a web extension that hides distracting feeds!",
  "browser_action": {
    "default_icon": "icons/logo.png",
    "default_title": "Focused Browsing",
    "default_popup": "html/popup.html"
  },
  "icons": {
    "16": "icons/logox16.png",
    "48": "icons/logox48.png",
    "128": "icons/logox128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "commands": {
    "focus-feature": {
      "suggested_key": {
        "default": "Ctrl+Shift+1"
      },
      "description": "Send a 'toggle-feature' event to the extension"
    }
  },
  "web_accessible_resources": [
    "html/*",
    "js/*",
    "css/*",
    "<all_urls>"
  ],
  "permissions": [
    "*://*.twitter.com/*",
    "*://*.linkedin.com/*",
    "*://*.youtube.com/*",
    "tabs",
    "storage"
  ]
}