event-rewrite: Clean up how events are rewritten.

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 3163c4cf68b8b86a8ebe654c6216328d9d2aca2c..4b8247ca113aea7229e409dad9fe713709d2ca09 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -328,9 +328,6 @@ class ASH_EXPORT Shell
   views::corewm::TooltipController* tooltip_controller() {
     return tooltip_controller_.get();
   }
-  internal::EventRewriterEventFilter* event_rewriter_filter() {
-    return event_rewriter_filter_.get();
-  }
   internal::OverlayEventFilter* overlay_filter() {
     return overlay_filter_.get();
   }
@@ -659,9 +656,6 @@ class ASH_EXPORT Shell
       event_transformation_handler_;
   scoped_ptr<WindowTreeHostFactory> root_window_host_factory_;
 
-  // An event filter that rewrites or drops an event.
-  scoped_ptr<internal::EventRewriterEventFilter> event_rewriter_filter_;
-
   // An event filter that pre-handles key events while the partial
   // screenshot UI or the keyboard overlay is active.
   scoped_ptr<internal::OverlayEventFilter> overlay_filter_;