mac: Bookmark bar drag and drop bug.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.mm

Index: chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.mm
diff --git a/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.mm b/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.mm
index 5470084a14ea8d87d7c51e30cf88def87bb9df9b..c8972c4dde4bc1ecd22b99fe60737cb2bb697ac5 100644
--- a/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.mm
+++ b/chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_hover_state.mm
@@ -33,6 +33,9 @@
       // Note that we only schedule the open or close if we have no other tasks
       // currently pending.
 
+      // Since the new bookmark folder is not opened until the previous is
+      // closed, the NSDraggingDestination must provide continuous callbacks,
+      // even if the cursor isn't moving.
       if (hoverState_ == kHoverStateOpen) {
         // Close the old.
         [self scheduleCloseBookmarkFolderOnHoverButton];