Split ValueSerializer into separate Serializer and Deserializer classes.

base/json/json_file_value_serializer.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.
 
 #ifndef BASE_JSON_JSON_FILE_VALUE_SERIALIZER_H_
 #define BASE_JSON_JSON_FILE_VALUE_SERIALIZER_H_
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/values.h"
 
 class BASE_EXPORT JSONFileValueSerializer : public base::ValueSerializer {
  public:
-  // |json_file_path_| is the path of a file that will be source of the
-  // deserialization or the destination of the serialization.
-  // When deserializing, the file should exist, but when serializing, the
-  // serializer will attempt to create the file at the specified location.
+  // |json_file_path_| is the path of a file that will be destination of the
+  // serialization. The serializer will attempt to create the file at the
+  // specified location.
   explicit JSONFileValueSerializer(const base::FilePath& json_file_path);
 
   ~JSONFileValueSerializer() override;
 
   // DO NOT USE except in unit tests to verify the file was written properly.
   // We should never serialize directly to a file since this will block the
   // thread. Instead, serialize to a string and write to the file you want on
   // the file thread.
   //
   // Attempt to serialize the data structure represented by Value into
   // JSON.  If the return value is true, the result will have been written
   // into the file whose name was passed into the constructor.
   bool Serialize(const base::Value& root) override;
 
   // Equivalent to Serialize(root) except binary values are omitted from the
   // output.
   bool SerializeAndOmitBinaryValues(const base::Value& root);
 
+ private:
+  bool SerializeInternal(const base::Value& root, bool omit_binary_values);
+
+  const base::FilePath json_file_path_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSONFileValueSerializer);
+};
+
+class BASE_EXPORT JSONFileValueDeserializer : public base::ValueDeserializer {
+ public:
+  // |json_file_path_| is the path of a file that will be source of the
+  // deserialization.
+  explicit JSONFileValueDeserializer(const base::FilePath& json_file_path);
+
+  ~JSONFileValueDeserializer() override;
+
   // Attempt to deserialize the data structure encoded in the file passed
   // in to the constructor into a structure of Value objects.  If the return
   // value is NULL, and if |error_code| is non-null, |error_code| will
   // contain an integer error code (either JsonFileError or JsonParseError).
   // If |error_message| is non-null, it will be filled in with a formatted
   // error message including the location of the error if appropriate.
   // The caller takes ownership of the returned value.
   base::Value* Deserialize(int* error_code,
                            std::string* error_message) override;
 
@@ skipping 13 matching lines @@
   static const char kNoSuchFile[];
 
   // Convert an error code into an error message.  |error_code| is assumed to
   // be a JsonFileError.
   static const char* GetErrorMessageForCode(int error_code);
 
   void set_allow_trailing_comma(bool new_value) {
     allow_trailing_comma_ = new_value;
   }
 
-  // Returns the syze (in bytes) of JSON string read from disk in the last
+  // Returns the size (in bytes) of JSON string read from disk in the last
   // successful |Deserialize()| call.
   size_t get_last_read_size() const { return last_read_size_; }
 
  private:
-  bool SerializeInternal(const base::Value& root, bool omit_binary_values);
+  // A wrapper for ReadFileToString which returns a non-zero JsonFileError if
+  // there were file errors.
+  int ReadFileToString(std::string* json_string);
 
   const base::FilePath json_file_path_;
   bool allow_trailing_comma_;
   size_t last_read_size_;
 
-  // A wrapper for ReadFileToString which returns a non-zero JsonFileError if
-  // there were file errors.
-  int ReadFileToString(std::string* json_string);
-
-  DISALLOW_IMPLICIT_CONSTRUCTORS(JSONFileValueSerializer);
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSONFileValueDeserializer);
 };
 
 #endif  // BASE_JSON_JSON_FILE_VALUE_SERIALIZER_H_