{
  "name" : "chrodic",
  "version" : "0.11",
  "description" : "A mouseover dictionary implementation",
  "homepage_url" : "http://d.hatena.ne.jp/kkishi/",
  "permissions" : [
    "http://*/*"
  ],
  "content_scripts" : [
    {
      "matches" : [ "http://*/*", "https://*/*" ],
      "js" : [ "chrodic.js" ],
      "all_frames" : true
    }
  ],
  "background" : {
    "scripts": ["background.js"]
  },
  "manifest_version" : 2
}

{
  "name" : "chrodic",
  "version" : "0.11",
  "description" : "A mouseover dictionary implementation",
  "homepage_url" : "http://d.hatena.ne.jp/kkishi/",
  "permissions" : [
    "http://*/*"
  ],
  "content_scripts" : [
    {
      "matches" : [ "http://*/*", "https://*/*" ],
      "js" : [ "chrodic.js" ],
      "all_frames" : true
    }
  ],
  "background" : {
    "scripts": ["background.js"],
    "persistent": false
  },
  "manifest_version" : 2
}

Make the background page non persistent. Confirmed it is quickly created by a first sendMessage call, and is unloaded by not calling sendMessage for a while.
Make the background page non persistent. Confirmed it is quickly created by a first sendMessage call, and is unloaded by not calling sendMessage for a while.
