Tweaking WebPageSerializerImpl to emit a BOM for UTF16/32.

third_party/WebKit/Source/web/WebPageSerializerImpl.h

 /*
  * Copyright (C) 2009 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 84 matching lines @@
     // file path.
     typedef HashMap<WTF::String, WTF::String> LinkLocalPathMap;
     // local_links_ include all pair of local resource path and corresponding
     // original link.
     LinkLocalPathMap m_localLinks;
     // Data buffer for saving result of serialized DOM data.
     StringBuilder m_dataBuffer;
     // Local directory name of all local resource files.
     WTF::String m_localDirectoryName;
 
+    // Tracks whether we've encoded any bytes yet.
+    bool m_noBytesEncodedYet;

[jsbell, 2015/12/07 22:53:51]

Can you flip the semantics of this so that it starts false and becomes true,
e.g. m_hasEncodedBytes ?

+
     // Web entities conversion maps.
     WebEntities m_htmlEntities;
     WebEntities m_xmlEntities;
 
     class SerializeDomParam {
         STACK_ALLOCATED();
     public:
         SerializeDomParam(const KURL&, const WTF::TextEncoding&, Document*, const WTF::String& directoryName);
 
         const KURL& url;
@@ skipping 56 matching lines @@
     void endTagToString(Element*,
                         SerializeDomParam* param);
     // Build content for a specified node
     void buildContentForNode(Node*,
                              SerializeDomParam* param);
 };
 
 } // namespace blink
 
 #endif