Fixing copresence/whispernet destructor order

Fixing copresence/whispernet destructor order

Committed: https://crrev.com/25eb568df53f2c5c3d406ab7ecfa89702317b169
Cr-Commit-Position: refs/heads/master@{#316615}

[Charlie, 2015-02-12 20:36:22]

ckehoe@chromium.org changed reviewers:
+ rkc@chromium.org

[Charlie, 2015-02-12 20:36:22]

The CopresenceDelegate is specific about Whispernet lasting longer than
CopresenceManager:

https://code.google.com/p/chromium/codesearch#chromium/src/components/coprese...

Accordingly, callbacks are unregistered in our destructors:

https://code.google.com/p/chromium/codesearch#chromium/src/components/coprese...

Yet the order of the manager and client seems backward in the API. In order to
be destructed *after* the manager, the whispernet client must appear *before*
it.

For some reason the current code does not crash, and neither does this new code.
However, using the current ordering in the modem API *does* crash. We might as
well be consistent.

[rkc, 2015-02-17 17:35:14]

lgtm

[Charlie, 2015-02-17 17:41:28]

The CQ bit was checked by ckehoe@chromium.org

[commit-bot: I haz the power, 2015-02-17 17:42:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/923533003/1

[commit-bot: I haz the power, 2015-02-17 18:43:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-17 18:43:52]

Patchset 1 (id:??) landed as
https://crrev.com/25eb568df53f2c5c3d406ab7ecfa89702317b169
Cr-Commit-Position: refs/heads/master@{#316615}