Tab dragging as implemented as a mus API.

components/mus/ws/window_manager_state.cc

Index: components/mus/ws/window_manager_state.cc
diff --git a/components/mus/ws/window_manager_state.cc b/components/mus/ws/window_manager_state.cc
index 8139b49a6d7fe4a01e87f7f18c4d1d2a129b52b4..1c31b8a01dadfcd931fcc31576343f3f5e406ee8 100644
--- a/components/mus/ws/window_manager_state.cc
+++ b/components/mus/ws/window_manager_state.cc
@@ -56,6 +56,12 @@ std::unique_ptr<ui::Event> CoalesceEvents(std::unique_ptr<ui::Event> first,
 
 }  // namespace
 
+struct WindowManagerState::CurrentMoveLoopState {
+  uint32_t change_id;
+  WindowId window_id;
+  gfx::Rect revert_bounds;
+};
+
 class WindowManagerState::ProcessedEventTarget {
  public:
   ProcessedEventTarget(ServerWindow* window,
@@ -129,6 +135,35 @@ bool WindowManagerState::SetCapture(ServerWindow* window,
   return event_dispatcher_.SetCaptureWindow(window, client_id);
 }
 
+void WindowManagerState::StartMoveLoop(uint32_t change_id,
+                                       WindowId window_id,
+                                       const gfx::Rect& revert_bounds) {
+  current_move_loop_.reset(
+      new CurrentMoveLoopState{change_id, window_id, revert_bounds});
+}
+
+void WindowManagerState::EndMoveLoop() {
+  current_move_loop_.reset();
+}
+
+uint32_t WindowManagerState::GetCurrentMoveLoopChangeId() {
+  if (current_move_loop_)
+    return current_move_loop_->change_id;
+  return 0;
+}
+
+WindowId WindowManagerState::GetCurrentMoveLoopWindowId() {
+  if (current_move_loop_)
+    return current_move_loop_->window_id;
+  return WindowId();
+}
+
+gfx::Rect WindowManagerState::GetCurrentMoveLoopRevertBounds() {
+  if (current_move_loop_)
+    return current_move_loop_->revert_bounds;
+  return gfx::Rect();
+}
+
 void WindowManagerState::ReleaseCaptureBlockedByModalWindow(
     const ServerWindow* modal_window) {
   event_dispatcher_.ReleaseCaptureBlockedByModalWindow(modal_window);