Examine source code of Hide-Em

{
  "manifest_version": 2,
  "name": "Hide-Em",
  "version": "1.3",
  "description": "Replace defined text strings and images with defaults",
  "icons": {
    "48": "icons/hide-em-48.svg",
    "96": "icons/hide-em-96.svg"
  },
  "permissions": [
    "storage",
    "activeTab"
  ],
  "browser_action": {
    "default_icon": {
      "19": "icons/hide-em-19.svg",
      "38": "icons/hide-em-38.svg"
    },
    "default_title": "Hide-Em",
    "default_popup": "popup/settings.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_scripts/replace.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background_scripts/background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cc00f788-313a-42c7-90e8-38c229062189}"
    }
  }
}