ash: Convert all remaining EventFilters into EventHandlers.

This CL converts the following list of aura::EventFilters into ui::EventHandlers:
 * MouseCursorEventFilter
 * DragDropController
 * LauncherTooltipManager
 * TooltipController
 * EventRewriterEventFilter
 * OverlayEventFilter
 * PanelWindowEventFilter
 * SystemModalContainerEventFilter
 * UserActivityDetector
 * WindowCycleEventFilter
 * WindowModalityController
 * FrameMaximizeButton::EscapeEventFilter
 * TabScrubber

Also remove AddEnvEventFilter/RemoveEnvEventFilter from Shell functions since
all the filters for the shell have been converted.

BUG=159632

Review URL: https://codereview.chromium.org/11366214

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@167399 0039d316-1c4b-4281-b951-d872f2087c98
32 files changed