Examine source code of Panel & Notifier for Gmail™

{
  "version": "0.1.6resigned1",
  "manifest_version": 2,
  "short_name": "gmailpanelnn",
  "name": "Panel & Notifier for Gmail™",
  "background": {
    "page": "lib/chrome/background.html"
  },
  "web_accessible_resources": [
    "data/content_script/*"
  ],
  "applications": {
    "gecko": {
      "strict_min_version": "53.0",
      "id": "jid1-w7wKyAFyu2OxRp@jetpack"
    }
  },
  "homepage_url": "http://mybrowseraddon.com/gmail-panel.html",
  "options_ui": {
    "chrome_style": true,
    "page": "data/options/options.html"
  },
  "description": "Easy access to Gmail via toolbar-popup UI, plus, get badge notifications.",
  "permissions": [
    "tabs",
    "storage",
    "<all_urls>",
    "webRequest",
    "webRequestBlocking"
  ],
  "browser_action": {
    "default_popup": "data/popup/popup.html",
    "default_title": "Panel & Notifier for Gmail™",
    "default_icon": {
      "16": "data/icons/16.png",
      "32": "data/icons/32.png"
    }
  },
  "content_scripts": [
    {
      "all_frames": true,
      "run_at": "document_start",
      "js": [
        "data/content_script/inject.js"
      ],
      "matches": [
        "*://*.mail.google.com/*",
        "*://*.accounts.google.com/*"
      ]
    }
  ],
  "icons": {
    "16": "data/icons/16.png",
    "32": "data/icons/32.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png"
  }
}