Tab dragging as implemented as a mus API.

components/mus/public/cpp/window_manager_delegate.h

Index: components/mus/public/cpp/window_manager_delegate.h
diff --git a/components/mus/public/cpp/window_manager_delegate.h b/components/mus/public/cpp/window_manager_delegate.h
index 99ddf34cc4e10daae412fa917ebd078bebe9c909..83679fb57f8530480dead71fc6a246561007ad9a 100644
--- a/components/mus/public/cpp/window_manager_delegate.h
+++ b/components/mus/public/cpp/window_manager_delegate.h
@@ -56,6 +56,8 @@ class WindowManagerClient {
       Window* window,
       const gfx::Vector2d& offset,
       const gfx::Insets& hit_area) = 0;
+  virtual void OnWmMoveLoopCompleted(uint32_t change_id,
+                                     bool completed) = 0;
 
  protected:
   virtual ~WindowManagerClient() {}
@@ -107,6 +109,12 @@ class WindowManagerDelegate {
 
   virtual void OnAccelerator(uint32_t id, const ui::Event& event) = 0;
 
+  virtual void OnWmPerformMoveLoop(uint32_t change_id,
+                                   uint32_t window_id,
+                                   const gfx::Point& cursor_location) = 0;
+
+  virtual void OnWmCancelMoveLoop(uint32_t window_id) = 0;
+
  protected:
   virtual ~WindowManagerDelegate() {}
 };