event-rewrite: Clean up how events are rewritten.

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 5a9f0242e9b7a19be92fd8b60451c18632342615..09e020bc5d7034e2cc688d433d694d936ae76f6f 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -58,7 +58,6 @@
 #include "ash/wm/coordinate_conversion.h"
 #include "ash/wm/custom_frame_view_ash.h"
 #include "ash/wm/event_client_impl.h"
-#include "ash/wm/event_rewriter_event_filter.h"
 #include "ash/wm/lock_state_controller.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/overlay_event_filter.h"
@@ -623,7 +622,6 @@ Shell::~Shell() {
   RemovePreTargetHandler(magnifier_key_scroller_.get());
   magnifier_key_scroller_.reset();
 #endif
-  RemovePreTargetHandler(event_rewriter_filter_.get());
   RemovePreTargetHandler(user_activity_detector_.get());
   RemovePreTargetHandler(overlay_filter_.get());
   RemovePreTargetHandler(input_method_filter_.get());
@@ -834,8 +832,6 @@ void Shell::Init() {
 #endif
 
   // The order in which event filters are added is significant.
-  event_rewriter_filter_.reset(new internal::EventRewriterEventFilter);
-  AddPreTargetHandler(event_rewriter_filter_.get());
 
 #if defined(OS_CHROMEOS)
   // The StickyKeysController also rewrites events and must be added