athena: Remove ActivityViewModel::CreateWidget().

athena: Remove ActivityViewModel::CreateWidget().

Use the existing views API (views::Widget::GetWidgetForNativeView()) to
get any existing views::Widget for an athena::Activity, instead of asking
its ActivityViewModel.

BUG=none
R=oshima@chromium.org

Committed: https://crrev.com/03222bda6cf957c899b7b312d53d7af80a6bc167
Cr-Commit-Position: refs/heads/master@{#302523}

[sadrul, 2014-11-03 23:10:24]

sadrul@chromium.org changed reviewers:
+ oshima@chromium.org

[oshima, 2014-11-03 23:44:08]

lgtm

[sadrul, 2014-11-03 23:57:29]

Committed patchset #1 (id:1) manually as
03222bda6cf957c899b7b312d53d7af80a6bc167 (presubmit successful).

[commit-bot: I haz the power, 2014-11-03 23:57:32]

Patchset 1 (id:??) landed as
https://crrev.com/03222bda6cf957c899b7b312d53d7af80a6bc167
Cr-Commit-Position: refs/heads/master@{#302523}