Scaling scroll/fling events in multi-monitor setup

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 48f4350ed780e965614cdf026aaf3698ea4211a1..b88c7329d1471bf3178bdeed85b4c328bca07752 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -15,6 +15,7 @@
 #include "ash/desktop_background/user_wallpaper_delegate.h"
 #include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
+#include "ash/display/event_transformation_handler.h"
 #include "ash/display/mouse_cursor_event_filter.h"
 #include "ash/display/screen_position_controller.h"
 #include "ash/drag_drop/drag_drop_controller.h"
@@ -469,6 +470,9 @@ void Shell::Init() {
   AddPreTargetHandler(accelerator_filter_.get());
 #endif
 
+  event_transformation_handler_.reset(new internal::EventTransformationHandler);
+  AddPreTargetHandler(event_transformation_handler_.get());
+
   system_gesture_filter_.reset(new internal::SystemGestureEventFilter);
   AddPreTargetHandler(system_gesture_filter_.get());