Tab dragging as implemented as a mus API.

components/mus/ws/test_utils.h

Index: components/mus/ws/test_utils.h
diff --git a/components/mus/ws/test_utils.h b/components/mus/ws/test_utils.h
index ede927722ecff2659c8b5f49fd4c190b134d7d17..3fdeb4cf79f6925fa75b84a27a49cf5817577159 100644
--- a/components/mus/ws/test_utils.h
+++ b/components/mus/ws/test_utils.h
@@ -262,6 +262,7 @@ class TestWindowManager : public mojom::WindowManager {
     return true;
   }
 
+  bool on_perform_move_loop_called() { return on_perform_move_loop_called_; }
   bool on_accelerator_called() { return on_accelerator_called_; }
   uint32_t on_accelerator_id() { return on_accelerator_id_; }
 
@@ -284,8 +285,15 @@ class TestWindowManager : public mojom::WindowManager {
       mojo::Map<mojo::String, mojo::Array<uint8_t>> properties) override;
   void WmClientJankinessChanged(ClientSpecificId client_id,
                                 bool janky) override;
+  void WmPerformMoveLoop(uint32_t change_id,
+                         uint32_t window_id,
+                         ::mus::mojom::MoveLoopSource source,
+                         const gfx::Point& cursor_location) override;
+  void WmCancelMoveLoop(uint32_t window_id) override;
   void OnAccelerator(uint32_t id, std::unique_ptr<ui::Event> event) override;
 
+  bool on_perform_move_loop_called_ = false;
+
   bool got_create_top_level_window_;
   uint32_t change_id_;