Tab dragging as implemented as a mus API.

services/ui/test_wm/test_wm.cc

Index: services/ui/test_wm/test_wm.cc
diff --git a/services/ui/test_wm/test_wm.cc b/services/ui/test_wm/test_wm.cc
index 0008ebeeb8555f7d4bb314598ff83707c41ef329..8739c1ffbc717f40770d6e8be7d47d5cc9a2c6e4 100644
--- a/services/ui/test_wm/test_wm.cc
+++ b/services/ui/test_wm/test_wm.cc
@@ -89,6 +89,13 @@ class TestWM : public shell::Service,
   void OnAccelerator(uint32_t id, const ui::Event& event) override {
     // Don't care.
   }
+  void OnWmPerformMoveLoop(Window* window,
+                           mojom::MoveLoopSource source,
+                           const gfx::Point& cursor_location,
+                           const base::Callback<void(bool)>& on_done) override {
+    // Don't care.
+  }
+  void OnWmCancelMoveLoop(Window* window) override {}
 
   ui::Window* root_ = nullptr;
   ui::WindowManagerClient* window_manager_client_ = nullptr;