Revert of Have Notifications appear over docked windows

Revert of Have Notifications appear over docked windows (patchset #4 id:60001 of https://codereview.chromium.org/1121893004/)

Reason for revert:
varkha@ noticed that this change will cause the virtual keyboard to obscure the notifications. Which I confirmed on my local branch.

Reverting before the regression is released.

I'll work on a followup change that also accounts for the keyboard region.

Original issue's description:
> Have Notifications appear over docked windows
>
> Update AshPopupAlignmentDelegate calculations of its work area.
>
> When windows are docked this reduces the work area for windows.
> AshPopupAlignmentDelegate uses the work area to determine the positioning of
> notifications. Update this calculation to include the docked region.
>
> TEST=AshPopupAlignmentDelegateTest.DockedWindow
> BUG=284574
>
> Committed: https://crrev.com/5b4e72c6ad0924d64d5eb9a10e063bc9334e95b2
> Cr-Commit-Position: refs/heads/master@{#329486}

TBR=oshima@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=284574
Committed: https://crrev.com/d42d4b2b547f8adbc7ac47e3eb20085901217f63
Cr-Commit-Position: refs/heads/master@{#329508}

[jonross, 2015-05-12 22:18:53]

Created Revert of Have Notifications appear over docked windows

[commit-bot: I haz the power, 2015-05-12 22:20:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1135323002/1

[commit-bot: I haz the power, 2015-05-12 22:22:36]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-12 22:23:23]

Patchset 1 (id:??) landed as
https://crrev.com/d42d4b2b547f8adbc7ac47e3eb20085901217f63
Cr-Commit-Position: refs/heads/master@{#329508}