[Extension API Extern Generation] Add support for function types

[Extension API Extern Generation] Add support for function types

Instead of just having Function or Function= for each callback, use the
function() Closure Compiler type documentation.  Additionally, add support for
@deprecated function documentation.

BUG=461039
Committed: https://crrev.com/7fbd4963fddcac58bf29762d85e96b42562e5c64
Cr-Commit-Position: refs/heads/master@{#322285}

[Devlin, 2015-03-25 16:17:13]

Patchset #1 (id:1) has been deleted

[Devlin, 2015-03-25 16:17:40]

rdevlin.cronin@chromium.org changed reviewers:
+ dbeam@chromium.org

[Devlin, 2015-03-25 16:17:41]

Dan, please take a look when you can.

Tyler, just FYI.

[Dan Beam, 2015-03-25 23:27:54]

lgtm++

[Devlin, 2015-03-25 23:36:58]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2015-03-25 23:38:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1036593004/20001

[commit-bot: I haz the power, 2015-03-26 01:07:27]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-03-26 01:08:02]

Patchset 1 (id:??) landed as
https://crrev.com/7fbd4963fddcac58bf29762d85e96b42562e5c64
Cr-Commit-Position: refs/heads/master@{#322285}