Check cookie and cache policy in renderer-side loading.

[Chikdolman]

Cookie policies and cache policies in current Chromium architecture may not be suitable for Castanets. For instance,

1. Should fetch cache from browser-side? Would it be faster than reading from server-side?
2. Should cache be on renderer-side? What if renderer device changes?
3. Should we drop cache policy and always read from the server?

We need to think and decide the right policy for castanets.