Revert 234978 "Added permission for chrome.app.window alwaysOnTo..."

> Added permission for chrome.app.window alwaysOnTop property
> 
> Apps that wish to enable the alwaysOnTop property for app windows must
> now declare the "alwaysOnTopWindows" permission in their manifest.
> This permission does not appear in install prompts.
> 
> BUG=314260, 171597
> TEST=browser_tests (PlatformAppBrowserTest.WindowsApiAlwaysOnTop*).
> Manual test: Create an app which does not specify this permission and
> attempts to create a new window with the option enabled or calls
> setAlwaysOnTop(true) on an existing window. The window should not be
> always on top. The option should work for apps which do declare the
> permission.
> 
> Review URL: https://codereview.chromium.org/68423003

This could not be merged into M32. We need to limit the always on top feature
more, which will not merge into M32 with this change, so this is being
reverted temporarily.

TBR=tmdiep@chromium.org

Review URL: https://codereview.chromium.org/62803005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235279 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235279