Tab dragging as implemented as a mus API.

components/mus/ws/window_tree.h

Index: components/mus/ws/window_tree.h
diff --git a/components/mus/ws/window_tree.h b/components/mus/ws/window_tree.h
index 9ef59aca9666d68c9ee7e903e411e9c3391e2316..5b1a5561b7b71063d809b64637584cfdd0f3acff 100644
--- a/components/mus/ws/window_tree.h
+++ b/components/mus/ws/window_tree.h
@@ -170,6 +170,7 @@ class WindowTree : public mojom::WindowTree,
   void OnWindowManagerCreatedTopLevelWindow(uint32_t wm_change_id,
                                             uint32_t client_change_id,
                                             const ServerWindow* window);
+  void OnMoveLoopCompleted(uint32_t client_change_id, bool completed);
   void AddActivationParent(const ClientWindowId& window_id);
 
   // Calls through to the client.
@@ -398,6 +399,10 @@ class WindowTree : public mojom::WindowTree,
       override;
   void GetCursorLocationMemory(const GetCursorLocationMemoryCallback& callback)
       override;
+  void PerformWindowMove(uint32_t change_id,
+                         Id window_id,
+                         const gfx::Point& cursor) override;
+  void CancelWindowMove(Id window_id) override;
 
   // mojom::WindowManagerClient:
   void AddAccelerator(uint32_t id,
@@ -420,6 +425,8 @@ class WindowTree : public mojom::WindowTree,
                             mojom::Cursor cursor_id) override;
   void OnWmCreatedTopLevelWindow(uint32_t change_id,
                                  Id transport_window_id) override;
+  void OnWmMoveLoopCompleted(uint32_t change_id,
+                             bool succeeded) override;
 
   // AccessPolicyDelegate:
   bool HasRootForAccessPolicy(const ServerWindow* window) const override;