Set AppActivityProxy window name for better Ctrl+Shift+Alt+W output

Set AppActivityProxy window name for better Ctrl+Shift+Alt+W output

To call GetWindow(), make overridden methods of AppActivityProxy public.
(this should be OK as AppActivity is doing the same thing and these methods become public with static_cast<Activity*>).

BUG=None

Committed: https://crrev.com/448146f6973ea1850e8beccf9c921c97c48b8a1b
Cr-Commit-Position: refs/heads/master@{#302028}

[hashimoto, 2014-10-29 06:01:58]

hashimoto@chromium.org changed reviewers:
+ skuhne@chromium.org

[Mr4D (OOO till 08-26), 2014-10-29 14:42:06]

lgtm

[hashimoto, 2014-10-30 03:27:48]

The CQ bit was checked by hashimoto@chromium.org

[commit-bot: I haz the power, 2014-10-30 03:28:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/659493007/1

[commit-bot: I haz the power, 2014-10-30 04:08:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-30 04:09:21]

Patchset 1 (id:??) landed as
https://crrev.com/448146f6973ea1850e8beccf9c921c97c48b8a1b
Cr-Commit-Position: refs/heads/master@{#302028}