Scaling scroll/fling events in multi-monitor setup

ash/shell.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/shell.h"
 
 #include <algorithm>
 #include <string>
 
 #include "ash/accelerators/focus_manager_factory.h"
 #include "ash/ash_switches.h"
 #include "ash/caps_lock_delegate.h"
 #include "ash/desktop_background/desktop_background_controller.h"
 #include "ash/desktop_background/desktop_background_view.h"
 #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"
 #include "ash/focus_cycler.h"
 #include "ash/high_contrast/high_contrast_controller.h"
 #include "ash/host/root_window_host_factory.h"
 #include "ash/launcher/launcher_delegate.h"
 #include "ash/launcher/launcher_model.h"
 #include "ash/magnifier/magnification_controller.h"
 #include "ash/magnifier/partial_magnification_controller.h"
@@ skipping 434 matching lines @@
 
   input_method_filter_.reset(new views::corewm::InputMethodEventFilter(
                                  root_window->GetAcceleratedWidget()));
   AddPreTargetHandler(input_method_filter_.get());
 
 #if !defined(OS_MACOSX)
   accelerator_filter_.reset(new internal::AcceleratorFilter);
   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());
 
   capture_controller_.reset(new internal::CaptureController);
 
   internal::RootWindowController* root_window_controller =
       new internal::RootWindowController(root_window);
   root_window_controller->CreateContainers();
   root_window_controller->CreateSystemBackground(
       delegate_->IsFirstRunAfterBoot());
@@ skipping 440 matching lines @@
 ////////////////////////////////////////////////////////////////////////////////
 // Shell, aura::client::ActivationChangeObserver implementation:
 
 void Shell::OnWindowActivated(aura::Window* gained_active,
                               aura::Window* lost_active) {
   if (gained_active)
     active_root_window_ = gained_active->GetRootWindow();
 }
 
 }  // namespace ash