Revert of [Base] Use variadic template in callback_list.h (wave 1)

Revert of [Base] Use variadic template in callback_list.h (wave 1) (patchset #1 id:1 of https://codereview.chromium.org/618573002/)

Reason for revert:
Breaking compilation on windows with MSVC Express.

Original issue's description:
> [Base] Use variadic template in callback_list.h
>
> Replace pump.py generated base/callback_list.h with variadic template version.
>
> BUG=None
>
> Committed: https://crrev.com/a28756fae426023c53542f08c1bf80397a28f677
> Cr-Commit-Position: refs/heads/master@{#298529}

TBR=ajwong@chromium.org,tzik@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=None

Committed: https://crrev.com/69e698364a0a82a806fc5a4994c5f2040d1ff083
Cr-Commit-Position: refs/heads/master@{#300487}

[lfg, 2014-10-21 14:53:50]

Created Revert of [Base] Use variadic template in callback_list.h (wave 1)

[commit-bot: I haz the power, 2014-10-21 14:54:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/663083005/1

[commit-bot: I haz the power, 2014-10-21 14:55:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-21 14:56:15]

Patchset 1 (id:??) landed as
https://crrev.com/69e698364a0a82a806fc5a4994c5f2040d1ff083
Cr-Commit-Position: refs/heads/master@{#300487}

[Nico, 2014-11-20 01:13:15]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/744503002/ by thakis@chromium.org.

The reason for reverting is: We now don't support building with MSVC Express any
more. Do shout if this change causes problems for your compiler, though.

This is part of http://crbug.com/433164.