NOT FOR LANDING: Thread the needle through all webmodules.

third_party/WebKit/Source/web/agent/sample/sample_agent.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "web/agent/sample/sample_agent.h"
+
+#include "web/api/document.h"
+#include "web/api/element.h"
+
+namespace web {
+
+SampleAgent::SampleAgent(Frame* frame) : Agent(frame) {
+  Element* element = frame->GetFunkyElement();
+  if (!element)
+    return;
+  element->SetId("FUNKY!");
+  element->Before("YESS", "AWESOME!");
+  Document* document = frame->GetDocument();
+  if (!document)
+    return;
+  document->Write("THIS", "IS", "VARIADIC");
+
+  // Example of what you can do with the Variant.
+  auto current_script = document->GetCurrentScript();
+  if (!current_script)
+    return;
+
+  if (WTF::holds_alternative<blink::Member<SVGScriptElement>>(
+          current_script.value()))
+    return;
+
+  HTMLScriptElement* script =
+      WTF::get<blink::Member<HTMLScriptElement>>(current_script.value());
+  script->DoDummyThing();
+}
+
+}  // namespace web