title: Chrome extension with iframe: Domains, protocols and ports must match
body: <p>Manifesto version 2 and his new content_security_policy is now necessary for chrome extension.
  I read some docs about 'sandbox mode" which seems to be a workaround for inline javascripts, but I still have a big issue.</p>
  
  <p>After some refactoring, I got the following error:
  "Unsafe JavaScript attempt to access frame with URL chrome-extension://mafcgphdkdbjlngfndodameheehmfhac/eventpage.html from frame with URL chrome-extension://mafcgphdkdbjlngfndodameheehmfhac/DCE24DB153A80B735442BF97F168AE6C.cache.html. Domains, protocols and ports must match."</p>
  
  <p>I can't understand why 2 files from the same extension doesn't have the same "Domains, protocols and ports"!</p>
  
  <p>NB: Here is a part of my manifesto:</p>
  
  <pre><code>"permissions": [
          "http://*/",
          "tabs"
      ],
    "background": {
      "page": "eventpage.html",
      "persistent": false
    },
    "sandbox": {
      "pages": [
          "sandbox.html",
          "DCE24DB153A80B735442BF97F168AE6C.cache.html"
      ]
    }
  ...
  </code></pre>