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With the addition of more document metadata (i.e. properties), split
the sending of bookmarks and attachments so they don't get mixed up with
what will now be the actual metadata.

Additionally, don't send bookmarks or attachments if the document
doesn't have any.

Bug: 93619
Change-Id: I4c327c508cf55f207c5ef36239097e7d20a1571e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2608499
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840922}