Examine source code of Furigana Reader

{
  "manifest_version": 2,
  "name": "Furigana Reader",
  "version": "1.0.0",
  "description": "Shows furigana (hiragana reading) for selected Japanese text.",
  "author": "niceblackwinchesterice@.gmail.com",
  "icons": {
    "16": "img/off.svg",
    "48": "img/off.svg",
    "128": "img/off.svg"
  },
  "browser_action": {
    "default_icon": {
      "16": "img/off.svg",
      "32": "img/off.svg"
    },
    "default_title": "Toggle Hiragana"
  },
  "background": {
    "scripts": [
      "common/config.js",
      "vendor/kuromoji/kuromoji.js",
      "background/background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "js": [
        "common/config.js",
        "content/content.js"
      ],
      "css": [
        "styles/content.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "permissions": [
    "storage",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "hiragana-furigana@example.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}