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 64a1c349317712953c4b4aa39d61ccee93e4d086..5dec3ae6813ed12df4bab30d3659001a49cbc273 100644
--- a/components/mus/ws/window_tree.h
+++ b/components/mus/ws/window_tree.h
@@ -166,6 +166,7 @@ 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.
@@ -397,6 +398,10 @@ 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,
@@ -419,6 +424,9 @@ 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,
+                             Id transport_window_id,
+                             bool succeeded) override;
 
   // AccessPolicyDelegate:
   bool HasRootForAccessPolicy(const ServerWindow* window) const override;