mus: Implement ScreenMus::GetCursorScreenPoint().

components/mus/ws/user_display_manager.h

Index: components/mus/ws/user_display_manager.h
diff --git a/components/mus/ws/user_display_manager.h b/components/mus/ws/user_display_manager.h
index c17a7c6981a155821d53159ac3482e8ddaedc8ad..ec0eb72233d5159e96a4b0b28a937e9c637fa399 100644
--- a/components/mus/ws/user_display_manager.h
+++ b/components/mus/ws/user_display_manager.h
@@ -12,6 +12,7 @@
 #include "components/mus/ws/user_id.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 #include "mojo/public/cpp/bindings/interface_ptr_set.h"
+#include "ui/gfx/geometry/point.h"
 
 namespace mus {
 namespace ws {
@@ -39,6 +40,9 @@ class UserDisplayManager : public mojom::DisplayManager {
   // Called by Display prior to |display| being removed and destroyed.
   void OnWillDestroyDisplay(Display* display);
 
+  // Updates the location of the cursor on this user's display.
+  void OnMouseCursorLocationChanged(const gfx::Point& location);
+
  private:
   friend class test::UserDisplayManagerTestApi;
 
@@ -57,6 +61,8 @@ class UserDisplayManager : public mojom::DisplayManager {
 
   // Overriden from mojom::DisplayManager:
   void AddObserver(mojom::DisplayManagerObserverPtr observer) override;
+  void GetCursorScreenPoint(
+      const GetCursorScreenPointCallback& callback) override;
 
   ws::DisplayManager* display_manager_;
 
@@ -71,6 +77,8 @@ class UserDisplayManager : public mojom::DisplayManager {
   mojo::InterfacePtrSet<mojom::DisplayManagerObserver>
       display_manager_observers_;
 
+  gfx::Point mouse_location_;
+
   // Observer used for tests.
   mojom::DisplayManagerObserver* test_observer_ = nullptr;