Change Background, set custom wallpaper

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "version": "1.1",
  "name": "Change Background, set custom wallpaper",
  "description": "This extension sets custom background for web-page",
  "browser_action": {
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "options_page": "options.html",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "contentscript.js",
        "popup.js",
        "options.js"
      ]
    }
  ]
}