Examine source code of Style Injector

{
  "manifest_version": 2,
  "name": "Style Injector",
  "version": "1.0",
  "description": "Injects styles to sites",
  "permissions": [
    "<all_urls>",
    "activeTab",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "src/script.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "16": "src/icons/icon16.png",
      "32": "src/icons/icon32.png"
    },
    "default_title": "Style Injector"
  },
  "options_ui": {
    "page": "src/settings/index.html"
  },
  "icons": {
    "48": "src/icons/icon48.png",
    "128": "src/icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "style-injector@stuff7.github.io"
    }
  }
}