Denote

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "name": "Denote",
  "description": "Displays reblogs with comments on tumblr posts.",
  "version": "0.3.0",
  "permissions": [
    "http://*.tumblr.com/post/*"
  ],
  "browser_action": {
    "default_icon": "images/icon.png",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://*.tumblr.com/post/*"
      ],
      "js": [
        "js/contentscript.js"
      ],
      "run_at": "document_end"
    }
  ]
}