Revert 266616 "Move DefaultActivationClient to wm/core"

Revert 266616 "Move DefaultActivationClient to wm/core"

> Move DefaultActivationClient to wm/core
> 
> Several tests are using AuraTestHelper and were relying on it to set up the DefaultActivationClient, so I had to have them instantiate the DAC directly after calling SetUp() on the helper. I also had to make the DAC delete itself after the root window it's bound to is destroyed.
> 
> R=sky@chromium.org
> http://crbug.com/308710
> 
> Review URL: https://codereview.chromium.org/250113002

TBR=ben@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=266632

[Ben Goodger (Google), 2014-04-28 19:46:25]

Committed patchset #1 manually as r266632 (tree was closed).