Tab dragging as implemented as a mus API.

ash/mus/window_manager.cc

Index: ash/mus/window_manager.cc
diff --git a/ash/mus/window_manager.cc b/ash/mus/window_manager.cc
index 3be7ba8a1dee8a33e9aca00f3fa46e8ac4e5b951..bd483355aead76a4d9748308f4119ac8c2708f31 100644
--- a/ash/mus/window_manager.cc
+++ b/ash/mus/window_manager.cc
@@ -240,5 +240,15 @@ void WindowManager::OnAccelerator(uint32_t id, const ui::Event& event) {
   }
 }
 
+void WindowManager::OnWmPerformMoveLoop(uint32_t change_id,
+                                        uint32_t window_id,
+                                        const gfx::Point& cursor_location) {
+  NOTIMPLEMENTED();
+}
+
+void WindowManager::OnWmCancelMoveLoop(uint32_t window_id) {
+  NOTIMPLEMENTED();
+}
+
 }  // namespace mus
 }  // namespace ash