Examine source code of Memory Game Basic Fun

{
  "manifest_version": 2,
  "name": "Memory Game Basic Fun",
  "version": "1.0",
  "description": "The memory game is a common children's game played with a set of cards. The cards have a pictures on one side and each picture appears on two (or sometimes four) cards. The game starts with all the cards face down and players take turns to turn over two cards. If the two cards have the same picture, then they keep the cards, otherwise they turn the cards face down again. The winner is the person with the most cards when all the cards have been taken.",
  "permissions": [],
  "browser_action": {
    "default_popup": "memory.html",
    "default_icon": {
      "128": "images/memo-logo.png"
    }
  },
  "icons": {
    "128": "images/memo-logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{188c6ea1-4cef-4dc7-8987-08e17311e25c}"
    }
  }
}