Examine source code of EmojiReplacer

{
  "manifest_version": 2,
  "name": "Emoji Replacer",
  "version": "1.0",
  "description": "Replaces certain words with emojis.",
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{195ead94-ae61-4373-a599-6faf096b1e76}"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "emoji.js"
      ]
    }
  ]
}