Allow tests within WebKit to implicitly convert WebCString to std::string.

public/platform/WebCString.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 WebCString_h
 #define WebCString_h
 
 #include "WebCommon.h"
 #include "WebPrivatePtr.h"
 
 #if INSIDE_WEBKIT
 #include <wtf/Forward.h>
-#else
+#endif
+#if !INSIDE_WEBKIT || defined(UNIT_TEST)
 #include <string>
 #endif
 
 namespace WTF {
 class CString;
 class CStringBuffer;
 }
 
 namespace WebKit {
 
@@ skipping 38 matching lines @@
     bool isEmpty() const { return !length(); }
     bool isNull() const { return m_private.isNull(); }
 
     BLINK_COMMON_EXPORT WebString utf16() const;
 
 #if INSIDE_WEBKIT
     BLINK_COMMON_EXPORT WebCString(const WTF::CString&);
     BLINK_COMMON_EXPORT WebCString& operator=(const WTF::CString&);
     BLINK_COMMON_EXPORT operator WTF::CString() const;
 #else
     WebCString(const std::string& s)

[Jeffrey Yasskin, 2013/07/11 20:32:40]

Defining these constructors in webkit tests causes an ambiguity for
WebCString("literal string"), so I left them out. operator string and fromUTF16
compiled fine.

     {
         assign(s.data(), s.length());
     }
 
     WebCString& operator=(const std::string& s)
     {
         assign(s.data(), s.length());
         return *this;
     }
-
+#endif
+#if !INSIDE_WEBKIT || defined(UNIT_TEST)
     operator std::string() const
     {
         size_t len = length();
         return len ? std::string(data(), len) : std::string();
     }
 
     template <class UTF16String>
     static WebCString fromUTF16(const UTF16String& s)
     {
         return fromUTF16(s.data(), s.length());
     }
 #endif
 
 private:
     BLINK_COMMON_EXPORT void assign(WTF::CStringBuffer*);
     WebPrivatePtr<WTF::CStringBuffer> m_private;
 };
 
 inline bool operator<(const WebCString& a, const WebCString& b)
 {
     return a.compare(b) < 0;
 }
 
 } // namespace WebKit
 
 #endif