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 53a4aed4c85c10d18df478675a8df53edd0c021f..b9222a6706c53818432e504cddbf616014f05c96 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -327,9 +327,6 @@ 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();
   }
@@ -658,9 +655,6 @@ class ASH_EXPORT Shell
       event_transformation_handler_;
   scoped_ptr<WindowTreeHostFactory> window_tree_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_;