Revert 255151 "Make chrome_elf use thunks instead of function po..."
(Crashy on today's canary)
> Make chrome_elf use thunks instead of function pointers.
>
> 1. Add functionality to ServiceResolverThunk to copy a thunk without patching.
> 2. Move chrome_elf thunk-handling code to a common location.
> 3. Use a thunk instead of a f'n ptr for redirects.
>
> BUG=334379
>
> Review URL: https://codereview.chromium.org/
183833004
TBR=caitkp@chromium.org
Review URL: https://codereview.chromium.org/
189803007
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255703 0039d316-1c4b-4281-b951-d872f2087c98