Remove RelatedHistogramSet.

tracing/tracing/value/diagnostics/add_related_names.html

Index: tracing/tracing/value/diagnostics/add_related_names.html
diff --git a/tracing/tracing/value/diagnostics/add_related_names.html b/tracing/tracing/value/diagnostics/add_related_names.html
index b276912bbb27f558802e228f1d2ad584c0a91552..a8151222466af3d9c73107fdb1814e018a4b77ca 100644
--- a/tracing/tracing/value/diagnostics/add_related_names.html
+++ b/tracing/tracing/value/diagnostics/add_related_names.html
@@ -20,11 +20,6 @@ tr.exportTo('tr.v.d', function() {
     for (const hist of histograms) {
       const relatedNames = new Set();
       for (const [name, diagnostic] of hist.diagnostics) {
-        if (diagnostic instanceof tr.v.d.RelatedHistogramSet) {
-          for (const relatedHist of diagnostic) {
-            relatedNames.add(relatedHist.name);
-          }
-        }
         if (diagnostic instanceof tr.v.d.RelatedHistogramMap) {
           for (const [relationshipName, relatedHist] of diagnostic) {
             relatedNames.add(relatedHist.name);