ScreenSaver: Get rid of gratuitous complexity

Screensaver isn't instantiated, so we don't really have any reason to go
through fancy class trickery to do this (as cool as it looked ;p)...

frontend/ui/screensaver.lua

@@ -805,18 +805,6 @@ function Screensaver:show()
         self.screensaver_widget.modal = true
         self.screensaver_widget.dithered = true
 
-        -- NOTE: ScreenSaver itself is not a widget, so make sure we cleanup behind us...
-        self.screensaver_widget.onCloseWidget = function(this)
-            -- this is self.screensaver_widget (i.e., an object instantiated from ScreenSaverWidget)
-            local super = getmetatable(this)
-            -- super is the class object of self.screensaver_widget (i.e., ScreenSaverWidget)
-            if super.onCloseWidget then
-                super.onCloseWidget(this)
-            end
-            -- self is ScreenSaver (upvalue)
-            self:cleanup()
-        end
-
         UIManager:show(self.screensaver_widget, "full")
     end
 
@@ -824,17 +812,6 @@ function Screensaver:show()
     if with_gesture_lock then
         self.screensaver_lock_widget = ScreenSaverLockWidget:new{}
 
-        -- If we don't have a ScreenSaverWidget handling cleanup for us, it'll fall to us...
-        if not self.screensaver_widget then
-            self.screensaver_lock_widget.onCloseWidget = function(this)
-                local super = getmetatable(this)
-                if super.onCloseWidget then
-                    super.onCloseWidget(this)
-                end
-                self:cleanup()
-            end
-        end
-
         -- It's flagged as modal, so it'll stay on top
         UIManager:show(self.screensaver_lock_widget)
     end

frontend/ui/widget/screensaverlockwidget.lua

@@ -120,6 +120,9 @@ function ScreenSaverLockWidget:onCloseWidget()
     local Screensaver = require("ui/screensaver")
     if not Screensaver.screensaver_widget then
         UIManager:setDirty("all", "full")
+
+        -- And take care of cleanup in its place, too
+        Screensaver:cleanup()
     end
 end
 

frontend/ui/widget/screensaverwidget.lua

@@ -97,6 +97,10 @@ function ScreenSaverWidget:onCloseWidget()
     -- Will come after the Resume event, iff screensaver_delay is set.
     -- Comes *before* it otherwise.
     UIManager:broadcastEvent(Event:new("OutOfScreenSaver"))
+
+    -- NOTE: ScreenSaver itself is neither a Widget nor an instantiated object, so make sure we cleanup behind us...
+    local Screensaver = require("ui/screensaver")
+    Screensaver:cleanup()
 end
 
 function ScreenSaverWidget:onResume()