Fix "defined but not used" warning in base/message_loop/message_loop.cc

Fix "defined but not used" warning in base/message_loop/message_loop.cc

PNaCl is being upgraded to Clang 3.4, which now warns about unused
declarations inside anonymous namespaces.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3757
TEST=compile using new PNaCl toolchain
R=darin@chromium.org, thakis@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=254690

[Mark Seaborn, 2014-03-03 16:39:13]

Putting an #if between two decls like this is obviously pretty ugly.  Is there
something cleaner I should do here?

[Mark Seaborn, 2014-03-03 21:39:51]

On 2014/03/03 16:39:13, Mark Seaborn wrote:
> Putting an #if between two decls like this is obviously pretty ugly.
> Is there something cleaner I should do here?

I've addressed that by using #if/#endif pairs so that one doesn't cross logical
blocks.

+thakis as reviewer.

[Nico, 2014-03-04 02:25:59]

lgtm

I like patch set 1 better fwiw.

[Mark Seaborn, 2014-03-04 03:01:58]

On 2014/03/04 02:25:59, Nico wrote:
> lgtm
> 
> I like patch set 1 better fwiw.

OK, reverted to patch set 1.  I don't mind either way.

[darin (slow to review), 2014-03-04 04:43:50]

Hmm, sadly this file is quite the #ifdef soup. There is probably some much
better refactoring of this code!

LGTM

[Mark Seaborn, 2014-03-04 06:06:32]

Committed patchset #3 manually as r254690 (presubmit successful).