Add UMA for popup overlays removed from saved MHTML page

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 52 matching lines @@
   STACK_ALLOCATED();
 
  public:
   enum ResourceHasCacheControlNoStoreHeader {
     kNoCacheControlNoStoreHeader,
     kHasCacheControlNoStoreHeader
   };
 
   class Delegate {
    public:
+    virtual ~Delegate() {}
+
     // Controls whether HTML serialization should skip the given element.
     virtual bool ShouldIgnoreElement(const Element&) { return false; }
 
     // Controls whether HTML serialization should skip the given attribute.
     virtual bool ShouldIgnoreAttribute(const Element&, const Attribute&) {
       return false;
     }
 
     // Method allowing the Delegate control which URLs are written into the
     // generated html document.
@@ skipping 64 matching lines @@
   HashSet<KURL> resource_urls_;
 
   bool is_serializing_css_;
 
   Delegate& delegate_;
 };
 
 }  // namespace blink
 
 #endif  // FrameSerializer_h