chrome/common/extensions/docs/examples/howto/contentscript_xhr/manifest.json

{
  "name": "Content Script Cross-Domain XMLHttpRequest Example",
  "version": "2.0.0",
  "description": "Demonstrates making cross domain requests from a content script by putting Twitter trends on Google News.",
  "permissions": [
    "https://api.twitter.com/*"
  ],
  "icons": {
    "48" : "sample-48.png",
    "128" : "sample-128.png"
  },
  "content_scripts": [
    {
      "matches": ["http://news.google.com/*"],
      "js" : ["contentscript.js"]
    }
  ]
}