Use a JS markup serializer.

sky/viewer/internals.cc

Index: sky/viewer/internals.cc
diff --git a/sky/viewer/internals.cc b/sky/viewer/internals.cc
index 9e51c9beff53ca22fb6293360d86b88e2e27454a..a4831eeb032f7b29eed4a3095ee4dcd0fa270421 100644
--- a/sky/viewer/internals.cc
+++ b/sky/viewer/internals.cc
@@ -45,7 +45,6 @@ gin::ObjectTemplateBuilder Internals::GetObjectTemplateBuilder(
   return Wrappable<Internals>::GetObjectTemplateBuilder(isolate)
       .SetMethod("renderTreeAsText", &Internals::RenderTreeAsText)
       .SetMethod("contentAsText", &Internals::ContentAsText)
-      .SetMethod("contentAsMarkup", &Internals::ContentAsMarkup)
       .SetMethod("notifyTestComplete", &Internals::NotifyTestComplete)
       .SetMethod("connectToService", &Internals::ConnectToService);
 }
@@ -63,12 +62,6 @@ std::string Internals::ContentAsText() {
       1024*1024).utf8();
 }
 
-std::string Internals::ContentAsMarkup() {
-  if (!document_view_)
-    return std::string();
-  return document_view_->web_view()->mainFrame()->contentAsMarkup().utf8();
-}
-
 void Internals::NotifyTestComplete(const std::string& test_result) {
   test_harness_->OnTestComplete(test_result);
 }