Examine source code of BrowserFaceCam

{
  "manifest_version": 2,
  "name": "BrowserCam",
  "version": "1.0",
  "description": "Creates a video element (with permission) on any page you visit that displays your face cam. Great for screensharing applications",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "BrowserCam",
    "default_popup": "settings.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "script.js"
      ]
    }
  ]
}