Add a nullable string16 class to base. It combines a string16 + a null param...

webkit/api/public/WebString.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 18 matching lines @@
  */
 
 #ifndef WebString_h
 #define WebString_h
 
 #include "WebCommon.h"
 
 #if WEBKIT_IMPLEMENTATION
 namespace WebCore { class String; class AtomicString; }
 #else
+#include <base/nullable_string16.h>
 #include <base/string16.h>
 #endif
 
 namespace WebKit {
     class WebCString;
     class WebStringPrivate;
 
     // A UTF-16 string container.  It is inexpensive to copy a WebString
     // object.
     //
@@ skipping 52 matching lines @@
             assign(s.data(), s.length());
             return *this;
         }
 
         operator string16() const
         {
             size_t len = length();
             return len ? string16(data(), len) : string16();
         }
 
+        WebString(const NullableString16& s) : m_private(0)
+        {
+            if (s.is_null())
+                assign(0);
+            else
+                assign(s.string().data(), s.string().length());
+        }
+
+        WebString& operator=(const NullableString16& s)
+        {
+            if (s.is_null())
+                assign(0);
+            else
+                assign(s.string().data(), s.string().length());
+            return *this;
+        }
+
+        operator NullableString16() const
+        {
+            if (!m_private)
+                return NullableString16(string16(), true);
+            size_t len = length();
+            return NullableString16(len ? string16(data(), len) : string16(), false);
+        }
+
         template <class UTF8String>
         static WebString fromUTF8(const UTF8String& s)
         {
             return fromUTF8(s.data(), s.length());
         }
 #endif
 
     private:
         void assign(WebStringPrivate*);
         WebStringPrivate* m_private;
     };
 
 } // namespace WebKit
 
 #endif