Revert 249095 "Refactor pref code out of ProfileImpl."

> Refactor pref code out of ProfileImpl.
> 
> Moved into the chrome_pref_service_factory.cc
> 
> ProfileImpl no longer has any notion of the Preferences file. This knowledge lives strictly in chrome_pref_service_factory.cc which now implements everything that needs to know about that file's path.
> 
> As per noms@'s request on https://codereview.chromium.org/145053004/
> 
> TBR=jochen (chrome/browser/chrome_browser_main.cc)
> 
> Review URL: https://codereview.chromium.org/154593002

TBR=gab@chromium.org

Review URL: https://codereview.chromium.org/156013003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249100 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249100