Make base::internal::CallbackBase::is_null inline.

Make base::internal::CallbackBase::is_null inline.

This saves 11 bytes per call site on x64-clang and 12 byte per call site on
ARM-gcc.

BUG=410776
TEST=base_unittests

Committed: https://crrev.com/caf874447fabaaee90921d611a052648ea150c70
Cr-Commit-Position: refs/heads/master@{#295215}

[Elliot Glaysher, 2014-09-04 17:02:54]

erg@chromium.org changed reviewers:
+ erg@chromium.org

[Elliot Glaysher, 2014-09-04 17:02:54]

not an owner, but as the person who usually waves the don't-inline-things flag,
this looks simple enough that I don't have any problems with it.

lgtm

[piman, 2014-09-05 17:55:21]

On 2014/09/04 17:02:54, Elliot Glaysher wrote:
> not an owner, but as the person who usually waves the don't-inline-things
flag,
> this looks simple enough that I don't have any problems with it.
> 
> lgtm

If it's measured to reduce code size, then it's a no brainer.
LGTM too, though I'm not an owner either.

[Adam Rice, 2014-09-08 04:25:21]

ricea@chromium.org changed reviewers:
+ thakis@chromium.org

[Adam Rice, 2014-09-08 04:25:21]

+thakis for base/ OWNERS.

[Adam Rice, 2014-09-16 12:09:43]

ping

[Nico, 2014-09-16 14:51:38]

lgtm

Sorry, I wasn't aware that you needed something from me here. (Also, when
pinging, say "ping: username", so that it's clear from the email who you're
pinging.)

[Adam Rice, 2014-09-17 01:10:46]

The CQ bit was checked by ricea@chromium.org

[commit-bot: I haz the power, 2014-09-17 01:11:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/540883002/1

[commit-bot: I haz the power, 2014-09-17 02:13:01]

Committed patchset #1 (id:1) as 6ee276ae6d801d9a0015385d41c9ba21418aa595

[commit-bot: I haz the power, 2014-09-17 02:13:36]

Patchset 1 (id:??) landed as
https://crrev.com/caf874447fabaaee90921d611a052648ea150c70
Cr-Commit-Position: refs/heads/master@{#295215}