Examine source code of FontBoost

{
  "manifest_version": 2,
  "name": "FontBoost",
  "version": "1.0",
  "description": "Extension to increase font size for selected text",
  "permissions": [
    "activeTab"
  ],
  "icons": {
    "16": "icon-16.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icon-16.png",
      "48": "icon-48.png",
      "128": "icon-128.png"
    },
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9f791c0f-6ffb-452d-8b14-356747f0778a}"
    }
  }
}