Add convenience methods for checking horizontal size class.

Add convenience methods for checking horizontal size class.

This CL adds methods to check for horizontal size class of views, view
controllers, etc.

BUG=527404
R=justincohen@chromium.org,rohitrao@chromium.org

Committed: https://crrev.com/ab739017d7ca888b9aba780b2f90afe318153c53
Cr-Commit-Position: refs/heads/master@{#347211}

[justincohen, 2015-09-02 15:11:16]

lgtm

[lpromero, 2015-09-02 17:28:24]

Ping Rohit

[lpromero, 2015-09-03 13:46:19]

lpromero@chromium.org changed reviewers:
+ pkl@chromium.org

[lpromero, 2015-09-03 13:46:20]

+pkl for OWNERS in Rohit's absence

[Eugene But (OOO till 7-30), 2015-09-03 18:49:40]

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

[Eugene But (OOO till 7-30), 2015-09-03 18:49:41]

lgtm

[justincohen, 2015-09-03 18:51:03]

The CQ bit was checked by justincohen@chromium.org

[justincohen, 2015-09-03 18:51:04]

The patchset sent to the CQ was uploaded after l-g-t-m from
justincohen@chromium.org
Link to the patchset: https://codereview.chromium.org/1329713002/#ps40001
(title: "Synced")

[commit-bot: I haz the power, 2015-09-03 18:51:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1329713002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1329713002/40001

[commit-bot: I haz the power, 2015-09-03 19:03:51]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-03 19:03:52]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[pkl (ping after 24h if needed), 2015-09-03 19:15:19]

lgtm

[justincohen, 2015-09-03 19:16:08]

The CQ bit was checked by justincohen@chromium.org

[commit-bot: I haz the power, 2015-09-03 19:16:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1329713002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1329713002/40001

[commit-bot: I haz the power, 2015-09-03 19:22:40]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-09-03 19:23:34]

Patchset 3 (id:??) landed as
https://crrev.com/ab739017d7ca888b9aba780b2f90afe318153c53
Cr-Commit-Position: refs/heads/master@{#347211}