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
SVN changes up to revision 255703