MD Bookmarks: Update Delete command to only delete the minimal set of nodes

This adds a filter so that when asking to delete a node at the same time
as one of its children, only the parent node will be explicitly deleted
(the child node will be implicitly deleted).

BUG=692827
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2850763002
Cr-Commit-Position: refs/heads/master@{#469612}
2 files changed