aura-mus: Hook up PerformWindowMove().

ui/aura/mus/window_tree_client.h

Index: ui/aura/mus/window_tree_client.h
diff --git a/ui/aura/mus/window_tree_client.h b/ui/aura/mus/window_tree_client.h
index cd62cfc90761b823d93436b2a9bb8d217b8dd32a..03f9f08817550da74a566d4ff42120a5949774d1 100644
--- a/ui/aura/mus/window_tree_client.h
+++ b/ui/aura/mus/window_tree_client.h
@@ -446,6 +446,13 @@ class AURA_EXPORT WindowTreeClient
   void OnWindowTreeHostStackAbove(WindowTreeHostMus* window_tree_host,
                                   Window* window) override;
   void OnWindowTreeHostStackAtTop(WindowTreeHostMus* window_tree_host) override;
+  void OnWindowTreeHostPerformWindowMove(
+      WindowTreeHostMus* window_tree_host,
+      ui::mojom::MoveLoopSource mus_source,
+      const gfx::Point& cursor_location,
+      const base::Callback<void(bool)>& callback) override;
+  void OnWindowTreeHostCancelWindowMove(
+      WindowTreeHostMus* window_tree_host) override;
   std::unique_ptr<WindowPortMus> CreateWindowPortForTopLevel(
       const std::map<std::string, std::vector<uint8_t>>* properties) override;
   void OnWindowTreeHostCreated(WindowTreeHostMus* window_tree_host) override;