Examine source code of Browser Calories

{
  "manifest_version": 2,
  "name": "Browser Calories",
  "description": "The easiest way to measure your performance budget",
  "homepage_url": "https://github.com/zenorocha/browser-calories",
  "version": "1.3.3resigned1",
  "applications": {
    "gecko": {
      "id": "calories@browserdiet.com",
      "strict_min_version": "45.0"
    }
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "images/icon-48.png"
  },
  "icons": {
    "16": "images/icon-16.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "https://www.googleapis.com/"
  ],
  "options_ui": {
    "page": "options.html",
    "chrome_style": true
  }
}