There are a bunch of UMA metrics under SBClientDownload.UnsupportedScheme.* has empty data. We might consider remove them.
SBClientDownload.UnsupportedScheme.JavaScriptScheme
SBClientDownload.UnsupportedScheme.GopherScheme
SBClientDownload.UnsupportedScheme.ContentScheme
SBClientDownload.UnsupportedScheme.FileSystemScheme
SBClientDownload.UnsupportedScheme.WSOrWSSScheme
SBClientDownload.UnsupportedScheme.ContentIdScheme
SBClientDownload.UnsupportedScheme.FtpScheme
SBClientDownload.UnsupportedScheme.RemoteFileScheme
Comment 1 by vakh@chromium.org
, Mar 16 2018