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The CL http://crrev.com/1638413003 will remove enhanced bookmarks but
the iOS code (and only the iOS code) dealing with bookmarks uses four
utility functions. This CL copies those functions to iOS before they
disapear.

BUG=None

Review URL: https://codereview.chromium.org/1647903002

Cr-Commit-Position: refs/heads/master@{#372081}