Mac: Fix compilation against the 10.12.1 SDK.

Mac: Fix compilation against the 10.12.1 SDK.

r433558 introduced a compile regression which bots and users of the
hermetic toolchain are insulated from. It deleted forward class
declarations required to suppress limited availability warnings when
compiling against the 10.12.1 SDK.

BUG=666893
TBR=sdy@chromium.org

[tapted, 2016-11-23 05:01:23]

Description was changed from

==========
whitespace


fixee

BUG=
==========

to

==========
Mac: Fix compilation against the 10.12.1 SDK.

r433558 introduced a compile regression which internal builders and
users of the hermetic toolchain are insulated from.

BUG=666893
TBR=sdy@chromium.org
==========

[tapted, 2016-11-23 05:01:24]

tapted@chromium.org changed reviewers:
+ sdy@chromium.org

[tapted, 2016-11-23 05:01:59]

Description was changed from

==========
Mac: Fix compilation against the 10.12.1 SDK.

r433558 introduced a compile regression which internal builders and
users of the hermetic toolchain are insulated from.

BUG=666893
TBR=sdy@chromium.org
==========

to

==========
Mac: Fix compilation against the 10.12.1 SDK.

r433558 introduced a compile regression which internal builders and
users of the hermetic toolchain are insulated from. It deleted forward
class declarations required to suppress limited availability warnings.

BUG=666893
TBR=sdy@chromium.org
==========

[tapted, 2016-11-23 05:02:11]

The CQ bit was checked by tapted@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-11-23 05:02:28]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[tapted, 2016-11-23 05:03:45]

Description was changed from

==========
Mac: Fix compilation against the 10.12.1 SDK.

r433558 introduced a compile regression which internal builders and
users of the hermetic toolchain are insulated from. It deleted forward
class declarations required to suppress limited availability warnings.

BUG=666893
TBR=sdy@chromium.org
==========

to

==========
Mac: Fix compilation against the 10.12.1 SDK.

r433558 introduced a compile regression which internal builders and
users of the hermetic toolchain are insulated from. It deleted forward
class declarations required to suppress limited availability warnings
when compiling against the 10.12.1 SDK.

BUG=666893
TBR=sdy@chromium.org
==========

[tapted, 2016-11-23 05:04:27]

Description was changed from

==========
Mac: Fix compilation against the 10.12.1 SDK.

r433558 introduced a compile regression which internal builders and
users of the hermetic toolchain are insulated from. It deleted forward
class declarations required to suppress limited availability warnings
when compiling against the 10.12.1 SDK.

BUG=666893
TBR=sdy@chromium.org
==========

to

==========
Mac: Fix compilation against the 10.12.1 SDK.

r433558 introduced a compile regression which bots and users of the
hermetic toolchain are insulated from. It deleted forward class
declarations required to suppress limited availability warnings when
compiling against the 10.12.1 SDK.

BUG=666893
TBR=sdy@chromium.org
==========