Examine source code of Tab Heatmap

{
  "manifest_version": 2,
  "name": "Tab Heatmap",
  "version": "1.2",
  "description": "Visualize tab usage with a heatmap that shows how hot or cold a tab is based on your usage!",
  "permissions": [
    "tabs",
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{805fbf00-5348-4542-a83c-7931892ee460}"
    }
  },
  "icons": {
    "48": "fireAndIceIcon.png"
  }
}