Support serializing shadow DOM to MHTML

third_party/WebKit/Source/core/frame/FrameSerializer.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 90 matching lines @@
     virtual bool ShouldSkipResource(ResourceHasCacheControlNoStoreHeader) {
       return false;
     }
 
     // Returns custom attributes that need to add in order to serialize the
     // element.
     virtual Vector<Attribute> GetCustomAttributes(const Element&) {
       return Vector<Attribute>();
     }
 
+    // Returns an auxiliary DOM tree, i.e. shadow tree, that needs to be
+    // serialized.
+    virtual std::pair<Node*, Element*> GetAuxiliaryDOMTree(
+        const Element&) const {
+      return std::pair<Node*, Element*>();
+    }
+
     virtual bool ShouldCollectProblemMetric() { return false; }
   };
 
   // Constructs a serializer that will write output to the given deque of
   // SerializedResources and uses the Delegate for controlling some
   // serialization aspects.  Callers need to ensure that both arguments stay
   // alive until the FrameSerializer gets destroyed.
   FrameSerializer(Deque<SerializedResource>&, Delegate&);
 
   // Initiates the serialization of the frame. All serialized content and
@@ skipping 38 matching lines @@
   int total_image_count_;
   int loaded_image_count_;
   int total_css_count_;
   int loaded_css_count_;
   bool should_collect_problem_metric_;
 };
 
 }  // namespace blink
 
 #endif  // FrameSerializer_h