MD Bookmarks: Batch updates to the UI when processing deletes and moves

chrome/browser/resources/md_bookmarks/dnd_manager.js

Index: chrome/browser/resources/md_bookmarks/dnd_manager.js
diff --git a/chrome/browser/resources/md_bookmarks/dnd_manager.js b/chrome/browser/resources/md_bookmarks/dnd_manager.js
index 71b1bcde1da76d1ec6d9c480ed6bf02d73021274..f742ad9de40f4a32e90bec173578e43d89ea7cb2 100644
--- a/chrome/browser/resources/md_bookmarks/dnd_manager.js
+++ b/chrome/browser/resources/md_bookmarks/dnd_manager.js
@@ -336,10 +336,13 @@ cr.define('bookmarks', function() {
         e.preventDefault();
 
         var dropInfo = this.calculateDropInfo_(this.dropDestination_);
-        if (dropInfo.index != -1)
-          chrome.bookmarkManagerPrivate.drop(dropInfo.parentId, dropInfo.index);
-        else
-          chrome.bookmarkManagerPrivate.drop(dropInfo.parentId);
+        var index = dropInfo.index != -1 ? dropInfo.index : undefined;
+        var store = bookmarks.Store.getInstance();
+        store.beginBatchUpdate();
+        chrome.bookmarkManagerPrivate.drop(

[calamity, 2017/06/22 05:48:27]

This works within the BMM, but moving a folder in the bookmarks bar will still
cause the burst of move events. Can we start the batch update in onDragEnter and
end it in onDrop instead?

[tsergeant, 2017/06/23 00:20:20]

Hmmm, good idea, but I'm not sure that this is possible.

When I drag BMM -> bookmarks bar, the chrome.bookmarksManagerPrivate.onDrop
listener never fires. Instead, we just get onDragLeave and then the
onBookmarkMoved calls.

Even dragging BMM->BMM doesn't work well, since the
bookmarksManagerPrivate.onDrop listener fires before the onBookmarkMoved calls.

[calamity, 2017/06/26 03:17:24]

Hmm. How about just batching in api_listener.js? Having a 100ms debouncer for
all events fired probably isn't unreasonable and would handle all EventStorms.

[tsergeant, 2017/06/27 07:35:53]

Done. As discussed, I setTimeout seems to work reliably on my machine. We'll
probably need to double check that it works okay on other machines as well after
this lands.

+            dropInfo.parentId, index, function() {
+              store.endBatchUpdate();
+            });
       }
 
       this.dropDestination_ = null;