Revert of Add a new status area control for Overview Mode. This control is only available (https://codereview.chromium.org/180743016/)

Reason for revert:
Somewhat speculative revert. This CL is one of two Ash-related CLs in the range where HideTooltipWhenCursorHidden in ash_unittests started failing:
http://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%282%29/builds/28144/steps/ash_unittests/logs/HideTooltipWhenCursorHidden

This looked most likely to be related to the failure to my untrained eye.

Original issue's description:
> Add a new status area control for Overview Mode. This control is only available while Maximize Mode is active.
> 
> BUG=337590
> TEST=OverviewModeTrayTest.*
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=256420

TBR=flackr@chromium.org,skuhne@chromium.org,oshima@chromium.org,sadrul@chromium.org,jonross@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=337590

Review URL: https://codereview.chromium.org/196603007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256535 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256535