Add an ostream operator to Value (based on JSONWriter) so that assertions

base/values.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file specifies a recursive data storage class called Value intended for
 // storing setting and other persistable data.  It includes the ability to
 // specify (recursive) lists and dictionaries, so it's fairly expressive.
 // However, the API is optimized for the common case, namely storing a
 // hierarchical tree of simple values.  Given a DictionaryValue root, you can
 // easily do things like:
@@ skipping 487 matching lines @@
 
   // This method deserializes the subclass-specific format into a Value object.
   // If the return value is non-NULL, the caller takes ownership of returned
   // Value. If the return value is NULL, and if error_code is non-NULL,
   // error_code will be set with the underlying error.
   // If |error_message| is non-null, it will be filled in with a formatted
   // error message including the location of the error if appropriate.
   virtual Value* Deserialize(int* error_code, std::string* error_str) = 0;
 };
 
+// Stream operator so Values can be used in assertion statements.
+BASE_EXPORT std::ostream& operator<<(std::ostream& out, const Value& value);
+
 }  // namespace base
 
 // http://crbug.com/88666
 using base::DictionaryValue;
 using base::ListValue;
 using base::StringValue;
 using base::Value;
 
 #endif  // BASE_VALUES_H_