Fixes possible crash in tab dragging

chrome/browser/ui/views/tabs/tab_drag_controller.cc

Index: chrome/browser/ui/views/tabs/tab_drag_controller.cc
diff --git a/chrome/browser/ui/views/tabs/tab_drag_controller.cc b/chrome/browser/ui/views/tabs/tab_drag_controller.cc
index 2ef2d96cc422aa56ed94edbfd9a74a38291a343d..b6dbafc92a3c24255bfb39d9aed7986d40db65d2 100644
--- a/chrome/browser/ui/views/tabs/tab_drag_controller.cc
+++ b/chrome/browser/ui/views/tabs/tab_drag_controller.cc
@@ -1358,7 +1358,8 @@ void TabDragController::EndDragImpl(EndDragType type) {
     }
   } else if (drag_data_.size() > 1) {
     initial_selection_model_.Clear();
-    RevertDrag();
+    if (started_drag_)
+      RevertDrag();
   }  // else case the only tab we were dragging was deleted. Nothing to do.
 
   // Clear out drag data so we don't attempt to do anything with it.