Move Ozone event stuff to ui/events

BUG=none
R=rjkroege@chromium.org

Review URL: https://codereview.chromium.org/23465037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224774 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224774
Revert 223982 "Remove GetActiveEntry usage from content."

> Remove GetActiveEntry usage from content.
> 
> Using GetActiveEntry can lead to subtle bugs, including security ones. See the bug entry for more details.
> 
> BUG=273710
> 
> Review URL: https://chromiumcodereview.appspot.com/23022006

TBR=nasko@chromium.org

Review URL: https://codereview.chromium.org/23800010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224775 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224775