Examine source code of DashboardMix

{
  "manifest_version": 2,
  "name": "DashboardMix",
  "description": "An extension to add elements to dashboards at DashboardMix.com",
  "version": "1.0.6",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "DashboardMix",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "css": [
        "content-scripts/content.css"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{07129684-71dd-4c87-b744-f3e67e71bb0f}"
    }
  }
}