Revert of Convert chart-json to Histograms.

tracing/tracing/results2_template.html

Index: tracing/tracing/results2_template.html
diff --git a/tracing/tracing/results2_template.html b/tracing/tracing/results2_template.html
index a651b3373770e238390d895ac9cd8cf3b3242505..2751afb9ad094cd966b3805dd1c6ae9294505b68 100644
--- a/tracing/tracing/results2_template.html
+++ b/tracing/tracing/results2_template.html
@@ -105,6 +105,7 @@
 
   removeJsonDivs_() {
     document.body.removeChild(this.jsonDivs_[0].parentNode);
+    delete this.jsonDivs_;
   }
 }
 
@@ -112,9 +113,6 @@
 
 document.addEventListener('DOMContentLoaded', () => {
   importer.importHistograms();
-
-  // Free the objects and DOM referenced by the importer.
-  importer = undefined;
 });
 
 })();