Examine source code of HighlightColor

{
  "manifest_version": 2,
  "name": "HighlightColor",
  "description": "Highlight color",
  "version": "2.1.2resigned1",
  "homepage_url": "https://github.com/chuck26/Highlight-Color",
  "permissions": [
    "storage"
  ],
  "icons": {
    "48": "icons/48-marker.svg"
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/48-marker.svg"
    },
    "default_title": "Highlight color"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "js/content_script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "color.highlight@gmail.com"
    }
  },
  "options_ui": {
    "page": "setting-page.html",
    "open_in_tab": true
  }
}