Tab dragging as implemented as a mus API.

components/mus/ws/window_server.cc

Index: components/mus/ws/window_server.cc
diff --git a/components/mus/ws/window_server.cc b/components/mus/ws/window_server.cc
index 77ef0e2595cf0366fadea9606cd8399f148a1b54..ce7f4460970d010d4812b56d463209a9ca0b5af0 100644
--- a/components/mus/ws/window_server.cc
+++ b/components/mus/ws/window_server.cc
@@ -30,6 +30,13 @@
 namespace mus {
 namespace ws {
 
+struct WindowServer::CurrentMoveLoopState {
+  uint32_t change_id;
+  ServerWindow* window;
+  WindowTree* initiator;
+  gfx::Rect revert_bounds;
+};
+
 WindowServer::WindowServer(
     WindowServerDelegate* delegate,
     const scoped_refptr<mus::SurfacesState>& surfaces_state)
@@ -324,6 +331,24 @@ void WindowServer::WindowManagerCreatedTopLevelWindow(
                                              change.client_change_id, window);
 }
 
+void WindowServer::WindowManagerCompletedMoveLoop(
+    uint32_t window_manager_change_id,
+    const ServerWindow* window,
+    bool completed) {
+  InFlightWindowManagerChange change;
+  if (!GetAndClearInFlightWindowManagerChange(window_manager_change_id,
+                                              &change)) {
+    return;
+  }
+  if (!window) {
+    WindowManagerSentBogusMessage();
+    return;
+  }
+
+  WindowTree* tree = GetTreeWithId(change.client_id);
+  tree->OnChangeCompleted(change.client_change_id, completed);
+}
+
 void WindowServer::ProcessWindowBoundsChanged(const ServerWindow* window,
                                               const gfx::Rect& old_bounds,
                                               const gfx::Rect& new_bounds) {
@@ -415,6 +440,42 @@ void WindowServer::SetPaintCallback(
   window_paint_callback_ = callback;
 }
 
+void WindowServer::StartMoveLoop(uint32_t change_id,
+                                 ServerWindow* window,
+                                 WindowTree* initiator,
+                                 const gfx::Rect& revert_bounds) {
+  current_move_loop_.reset(
+      new CurrentMoveLoopState{change_id, window, initiator, revert_bounds});
+}
+
+void WindowServer::EndMoveLoop() {
+  current_move_loop_.reset();
+}
+
+uint32_t WindowServer::GetCurrentMoveLoopChangeId() {
+  if (current_move_loop_)
+    return current_move_loop_->change_id;
+  return 0;
+}
+
+ServerWindow* WindowServer::GetCurrentMoveLoopWindow() {
+  if (current_move_loop_)
+    return current_move_loop_->window;
+  return nullptr;
+}
+
+WindowTree* WindowServer::GetCurrentMoveLoopInitiator() {
+  if (current_move_loop_)
+    return current_move_loop_->initiator;
+  return nullptr;
+}
+
+gfx::Rect WindowServer::GetCurrentMoveLoopRevertBounds() {
+  if (current_move_loop_)
+    return current_move_loop_->revert_bounds;
+  return gfx::Rect();
+}
+
 bool WindowServer::GetAndClearInFlightWindowManagerChange(
     uint32_t window_manager_change_id,
     InFlightWindowManagerChange* change) {