mash: make Env::last_mouse_location() accurate for Mus

ui/aura/window_event_dispatcher.h

Index: ui/aura/window_event_dispatcher.h
diff --git a/ui/aura/window_event_dispatcher.h b/ui/aura/window_event_dispatcher.h
index 219037c7938d35265208f386a1a6880cdc73be6c..32b2b905bf04d5180ee83fdc869db514437a9ee5 100644
--- a/ui/aura/window_event_dispatcher.h
+++ b/ui/aura/window_event_dispatcher.h
@@ -35,6 +35,7 @@ class TouchEvent;
 }
 
 namespace aura {
+class MusMouseLocationUpdater;
 class TestScreen;
 class EnvInputStateController;
 class WindowTreeHost;
@@ -174,6 +175,7 @@ class AURA_EXPORT WindowEventDispatcher : public ui::EventProcessor,
   // Overridden from ui::EventProcessor:
   ui::EventTarget* GetRootTarget() override;
   void OnEventProcessingStarted(ui::Event* event) override;
+  void OnEventProcessingFinished(ui::Event* event) override;
 
   // Overridden from ui::EventDispatcherDelegate.
   bool CanDispatchToTarget(ui::EventTarget* target) override;
@@ -258,6 +260,8 @@ class AURA_EXPORT WindowEventDispatcher : public ui::EventProcessor,
 
   std::unique_ptr<EnvInputStateController> env_controller_;
 
+  std::unique_ptr<MusMouseLocationUpdater> mus_mouse_location_updater_;
+
   // Used to schedule reposting an event.
   base::WeakPtrFactory<WindowEventDispatcher> repost_event_factory_;