Use std::tie() for operator< in extensions/

Use std::tie() for operator< in extensions/

Simplify the code for operator< when comparing multiple members using
a common std::tie idiom.

BUG=555171
R=rdevlin.cronin@chromium.org

Committed: https://crrev.com/9a9ef2b842828e764ad7e120b6563025d27bdaad
Cr-Commit-Position: refs/heads/master@{#360879}

[jsbell, 2015-11-19 22:19:57]

devlin - please take a look?

[Devlin, 2015-11-20 01:19:55]

lgtm!  So happy we can use this now.

[jsbell, 2015-11-20 19:01:34]

The CQ bit was checked by jsbell@chromium.org

[commit-bot: I haz the power, 2015-11-20 19:05:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1461163002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1461163002/1

[commit-bot: I haz the power, 2015-11-20 19:37:22]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-20 19:39:09]

Patchset 1 (id:??) landed as
https://crrev.com/9a9ef2b842828e764ad7e120b6563025d27bdaad
Cr-Commit-Position: refs/heads/master@{#360879}