Only display when it's different than the pre-populated
edit summary (Undo revision 123 by User).
Bug: T121808
Change-Id: I5a00ff174fd31fdbf776a06b7b9375f63b921677
They're currently auto-converted to the new format, but ideally,
we wouldn't need that B/C code. And since this is the extension
others will likely look at for examples when implementing, we
should do it right here.
Also: there is no B/C correction for missing keys in secondary
links (description, icon).
Change-Id: If1a8b9911e81bb4c565f21a4b9e31fdc73426d93
