Change the signature of JSONReader::Read() and related

methods to be more friendly to use with scoped_ptr. Change
all the callsites.

Review URL: http://codereview.chromium.org/16270

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@7486 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 307 insertions, 424 deletions

diff --git a/base/json_reader.cc b/base/json_reader.cc
index 2cea239..bf233a6 100644
--- a/base/json_reader.cc
+++ b/base/json_reader.cc
@@ -89,25 +89,24 @@ const char* JSONReader::kUnquotedDictionaryKey =
     "Dictionary keys must be quoted.";
 
 /* static */
-bool JSONReader::Read(const std::string& json,
-                      Value** root,
-                      bool allow_trailing_comma) {
-  return ReadAndReturnError(json, root, allow_trailing_comma, NULL);
+Value* JSONReader::Read(const std::string& json,
+                        bool allow_trailing_comma) {
+  return ReadAndReturnError(json, allow_trailing_comma, NULL);
 }
 
 /* static */
-bool JSONReader::ReadAndReturnError(const std::string& json,
-                                    Value** root,
-                                    bool allow_trailing_comma,
-                                    std::string *error_message_out) {
+Value* JSONReader::ReadAndReturnError(const std::string& json,
+                                      bool allow_trailing_comma,
+                                      std::string *error_message_out) {
   JSONReader reader = JSONReader();
-  if (reader.JsonToValue(json, root, true, allow_trailing_comma)) {
-    return true;
-  } else {
-    if (error_message_out)
-      *error_message_out = reader.error_message();
-    return false;
-  }
+  Value* root = reader.JsonToValue(json, true, allow_trailing_comma);
+  if (root)
+    return root;
+
+  if (error_message_out)
+    *error_message_out = reader.error_message();
+
+  return NULL;
 }
 
 /* static */
@@ -121,12 +120,12 @@ JSONReader::JSONReader()
   : start_pos_(NULL), json_pos_(NULL), stack_depth_(0),
     allow_trailing_comma_(false) {}
 
-bool JSONReader::JsonToValue(const std::string& json, Value** root,
-                             bool check_root, bool allow_trailing_comma) {
+Value* JSONReader::JsonToValue(const std::string& json, bool check_root,
+                               bool allow_trailing_comma) {
   // The input must be in UTF-8.
   if (!IsStringUTF8(json.c_str())) {
     error_message_ = kUnsupportedEncoding;
-    return false;
+    return NULL;
   }
 
   // The conversion from UTF8 to wstring removes null bytes for us
@@ -148,13 +147,10 @@ bool JSONReader::JsonToValue(const std::string& json, Value** root,
   stack_depth_ = 0;
   error_message_.clear();
 
-  Value* temp_root = NULL;
-
-  // Only modify root_ if we have valid JSON and nothing else.
-  if (BuildValue(&temp_root, check_root)) {
+  scoped_ptr<Value> root(BuildValue(check_root));
+  if (root.get()) {
     if (ParseToken().type == Token::END_OF_INPUT) {
-      *root = temp_root;
-      return true;
+      return root.release();
     } else {
       SetErrorMessage(kUnexpectedDataAfterRoot, json_pos_);
     }
@@ -164,16 +160,14 @@ bool JSONReader::JsonToValue(const std::string& json, Value** root,
   if (error_message_.empty())
     SetErrorMessage(kSyntaxError, json_pos_);
 
-  if (temp_root)
-    delete temp_root;
-  return false;
+  return NULL;
 }
 
-bool JSONReader::BuildValue(Value** node, bool is_root) {
+Value* JSONReader::BuildValue(bool is_root) {
   ++stack_depth_;
   if (stack_depth_ > kStackLimit) {
     SetErrorMessage(kTooMuchNesting, json_pos_);
-    return false;
+    return NULL;
   }
 
   Token token = ParseToken();
@@ -181,34 +175,38 @@ bool JSONReader::BuildValue(Value** node, bool is_root) {
   if (is_root && token.type != Token::OBJECT_BEGIN &&
       token.type != Token::ARRAY_BEGIN) {
     SetErrorMessage(kBadRootElementType, json_pos_);
-    return false;
+    return NULL;
   }
 
+  scoped_ptr<Value> node;
+
   switch (token.type) {
     case Token::END_OF_INPUT:
     case Token::INVALID_TOKEN:
-      return false;
+      return NULL;
 
     case Token::NULL_TOKEN:
-      *node = Value::CreateNullValue();
+      node.reset(Value::CreateNullValue());
       break;
 
     case Token::BOOL_TRUE:
-      *node = Value::CreateBooleanValue(true);
+      node.reset(Value::CreateBooleanValue(true));
       break;
 
     case Token::BOOL_FALSE:
-      *node = Value::CreateBooleanValue(false);
+      node.reset(Value::CreateBooleanValue(false));
       break;
 
     case Token::NUMBER:
-      if (!DecodeNumber(token, node))
-        return false;
+      node.reset(DecodeNumber(token));
+      if (!node.get())
+        return NULL;
       break;
 
     case Token::STRING:
-      if (!DecodeString(token, node))
-        return false;
+      node.reset(DecodeString(token));
+      if (!node.get())
+        return NULL;
       break;
 
     case Token::ARRAY_BEGIN:
@@ -216,14 +214,13 @@ bool JSONReader::BuildValue(Value** node, bool is_root) {
         json_pos_ += token.length;
         token = ParseToken();
 
-        ListValue* array = new ListValue;
+        node.reset(new ListValue());
         while (token.type != Token::ARRAY_END) {
-          Value* array_node = NULL;
-          if (!BuildValue(&array_node, false)) {
-            delete array;
-            return false;
+          Value* array_node = BuildValue(false);
+          if (!array_node) {
+            return NULL;
           }
-          array->Append(array_node);
+          static_cast<ListValue*>(node.get())->Append(array_node);
 
           // After a list value, we expect a comma or the end of the list.
           token = ParseToken();
@@ -235,23 +232,19 @@ bool JSONReader::BuildValue(Value** node, bool is_root) {
             if (token.type == Token::ARRAY_END) {
               if (!allow_trailing_comma_) {
                 SetErrorMessage(kTrailingComma, json_pos_);
-                delete array;
-                return false;
+                return NULL;
               }
               // Trailing comma OK, stop parsing the Array.
               break;
             }
           } else if (token.type != Token::ARRAY_END) {
             // Unexpected value after list value.  Bail out.
-            delete array;
-            return false;
+            return NULL;
           }
         }
         if (token.type != Token::ARRAY_END) {
-          delete array;
-          return false;
+          return NULL;
         }
-        *node = array;
         break;
       }
 
@@ -260,39 +253,32 @@ bool JSONReader::BuildValue(Value** node, bool is_root) {
         json_pos_ += token.length;
         token = ParseToken();
 
-        DictionaryValue* dict = new DictionaryValue;
+        node.reset(new DictionaryValue);
         while (token.type != Token::OBJECT_END) {
           if (token.type != Token::STRING) {
             SetErrorMessage(kUnquotedDictionaryKey, json_pos_);
-            delete dict;
-            return false;
-          }
-          Value* dict_key_value = NULL;
-          if (!DecodeString(token, &dict_key_value)) {
-            delete dict;
-            return false;
+            return NULL;
           }
+          scoped_ptr<Value> dict_key_value(DecodeString(token));
+          if (!dict_key_value.get())
+            return NULL;
+
           // Convert the key into a wstring.
           std::wstring dict_key;
           bool success = dict_key_value->GetAsString(&dict_key);
           DCHECK(success);
-          delete dict_key_value;
 
           json_pos_ += token.length;
           token = ParseToken();
-          if (token.type != Token::OBJECT_PAIR_SEPARATOR) {
-            delete dict;
-            return false;
-          }
+          if (token.type != Token::OBJECT_PAIR_SEPARATOR)
+            return NULL;
 
           json_pos_ += token.length;
           token = ParseToken();
-          Value* dict_value = NULL;
-          if (!BuildValue(&dict_value, false)) {
-            delete dict;
-            return false;
-          }
-          dict->Set(dict_key, dict_value);
+          Value* dict_value = BuildValue(false);
+          if (!dict_value)
+            return NULL;
+          static_cast<DictionaryValue*>(node.get())->Set(dict_key, dict_value);
 
           // After a key/value pair, we expect a comma or the end of the
           // object.
@@ -305,34 +291,30 @@ bool JSONReader::BuildValue(Value** node, bool is_root) {
             if (token.type == Token::OBJECT_END) {
               if (!allow_trailing_comma_) {
                 SetErrorMessage(kTrailingComma, json_pos_);
-                delete dict;
-                return false;
+                return NULL;
               }
               // Trailing comma OK, stop parsing the Object.
               break;
             }
           } else if (token.type != Token::OBJECT_END) {
             // Unexpected value after last object value.  Bail out.
-            delete dict;
-            return false;
+            return NULL;
           }
         }
-        if (token.type != Token::OBJECT_END) {
-          delete dict;
-          return false;
-        }
-        *node = dict;
+        if (token.type != Token::OBJECT_END)
+          return NULL;
+
         break;
       }
 
     default:
       // We got a token that's not a value.
-      return false;
+      return NULL;
   }
   json_pos_ += token.length;
 
   --stack_depth_;
-  return true;
+  return node.release();
 }
 
 JSONReader::Token JSONReader::ParseNumberToken() {
@@ -372,22 +354,18 @@ JSONReader::Token JSONReader::ParseNumberToken() {
   return token;
 }
 
-bool JSONReader::DecodeNumber(const Token& token, Value** node) {
+Value* JSONReader::DecodeNumber(const Token& token) {
   const std::wstring num_string(token.begin, token.length);
 
   int num_int;
-  if (StringToInt(num_string, &num_int)) {
-    *node = Value::CreateIntegerValue(num_int);
-    return true;
-  }
+  if (StringToInt(num_string, &num_int))
+    return Value::CreateIntegerValue(num_int);
 
   double num_double;
-  if (StringToDouble(num_string, &num_double) && base::IsFinite(num_double)) {
-    *node = Value::CreateRealValue(num_double);
-    return true;
-  }
+  if (StringToDouble(num_string, &num_double) && base::IsFinite(num_double))
+    return Value::CreateRealValue(num_double);
 
-  return false;
+  return NULL;
 }
 
 JSONReader::Token JSONReader::ParseStringToken() {
@@ -435,7 +413,7 @@ JSONReader::Token JSONReader::ParseStringToken() {
   return kInvalidToken;
 }
 
-bool JSONReader::DecodeString(const Token& token, Value** node) {
+Value* JSONReader::DecodeString(const Token& token) {
   std::wstring decoded_str;
   decoded_str.reserve(token.length - 2);
 
@@ -486,16 +464,14 @@ bool JSONReader::DecodeString(const Token& token, Value** node) {
           // We should only have valid strings at this point.  If not,
           // ParseStringToken didn't do it's job.
           NOTREACHED();
-          return false;
+          return NULL;
       }
     } else {
       // Not escaped
       decoded_str.push_back(c);
     }
   }
-  *node = Value::CreateStringValue(decoded_str);
-
-  return true;
+  return Value::CreateStringValue(decoded_str);
 }
 
 JSONReader::Token JSONReader::ParseToken() {
diff --git a/base/json_reader.h b/base/json_reader.h
index 2c9f27a..6231581 100644
--- a/base/json_reader.h
+++ b/base/json_reader.h
@@ -85,22 +85,19 @@ class JSONReader {
   static const char* kUnsupportedEncoding;
   static const char* kUnquotedDictionaryKey;
 
-  // Reads and parses |json| and populates |root|. If |json| is not a properly
-  // formed JSON string, returns false, leaves root unaltered and sets
-  // error_message if it was non-null. If allow_trailing_comma is true, we will
-  // ignore trailing commas in objects and arrays even though this goes against
-  // the RFC.
-  static bool Read(const std::string& json,
-                   Value** root,
-                   bool allow_trailing_comma);
+  // Reads and parses |json|, returning a Value. The caller owns the returned
+  // instance. If |json| is not a properly formed JSON string, returns NULL.
+  // If allow_trailing_comma is true, we will ignore trailing commas in objects
+  // and arrays even though this goes against the RFC.
+  static Value* Read(const std::string& json,
+                     bool allow_trailing_comma);
 
   // Reads and parses |json| like Read(). |error_message_out| is optional. If
-  // specified and false is returned, error_message_out will be populated with
+  // specified and NULL is returned, error_message_out will be populated with
   // a string describing the error. Otherwise, error_message_out is unmodified.
-  static bool ReadAndReturnError(const std::string& json,
-                                 Value** root,
-                                 bool allow_trailing_comma,
-                                 std::string *error_message_out);
+  static Value* ReadAndReturnError(const std::string& json,
+                                   bool allow_trailing_comma,
+                                   std::string *error_message_out);
 
  private:
   static std::string FormatErrorMessage(int line, int column,
@@ -118,13 +115,13 @@ class JSONReader {
 
   // Pass through method from JSONReader::Read.  We have this so unittests can
   // disable the root check.
-  bool JsonToValue(const std::string& json, Value** root, bool check_root,
-                   bool allow_trailing_comma);
+  Value* JsonToValue(const std::string& json, bool check_root,
+                     bool allow_trailing_comma);
 
-  // Recursively build Value.  Returns false if we don't have a valid JSON
+  // Recursively build Value.  Returns NULL if we don't have a valid JSON
   // string.  If |is_root| is true, we verify that the root element is either
   // an object or an array.
-  bool BuildValue(Value** root, bool is_root);
+  Value* BuildValue(bool is_root);
 
   // Parses a sequence of characters into a Token::NUMBER. If the sequence of
   // characters is not a valid number, returns a Token::INVALID_TOKEN. Note
@@ -133,9 +130,8 @@ class JSONReader {
   Token ParseNumberToken();
 
   // Try and convert the substring that token holds into an int or a double. If
-  // we can (ie., no overflow), return true and create the appropriate value
-  // for |node|.  Return false if we can't do the conversion.
-  bool DecodeNumber(const Token& token, Value** node);
+  // we can (ie., no overflow), return the value, else return NULL.
+  Value* DecodeNumber(const Token& token);
 
   // Parses a sequence of characters into a Token::STRING. If the sequence of
   // characters is not a valid string, returns a Token::INVALID_TOKEN. Note
@@ -146,7 +142,7 @@ class JSONReader {
   // Convert the substring into a value string.  This should always succeed
   // (otherwise ParseStringToken would have failed), but returns a success bool
   // just in case.
-  bool DecodeString(const Token& token, Value** node);
+  Value* DecodeString(const Token& token);
 
   // Grabs the next token in the JSON stream.  This does not increment the
   // stream so it can be used to look ahead at the next token.
diff --git a/base/json_reader_unittest.cc b/base/json_reader_unittest.cc
index 7ded39f..9153289 100644
--- a/base/json_reader_unittest.cc
+++ b/base/json_reader_unittest.cc
@@ -4,66 +4,55 @@
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "base/json_reader.h"
+#include "base/scoped_ptr.h"
 #include "base/values.h"
 #include "build/build_config.h"
 
 TEST(JSONReaderTest, Reading) {
   // some whitespace checking
-  Value* root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("   null   ", &root, false, false));
-  ASSERT_TRUE(root);
+  scoped_ptr<Value> root;
+  root.reset(JSONReader().JsonToValue("   null   ", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_NULL));
-  delete root;
 
   // Invalid JSON string
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("nu", &root, false, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader().JsonToValue("nu", false, false));
+  ASSERT_FALSE(root.get());
 
   // Simple bool
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("true  ", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("true  ", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_BOOLEAN));
-  delete root;
 
   // Test number formats
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("43", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("43", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_INTEGER));
   int int_val = 0;
   ASSERT_TRUE(root->GetAsInteger(&int_val));
   ASSERT_EQ(43, int_val);
-  delete root;
 
   // According to RFC4627, oct, hex, and leading zeros are invalid JSON.
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("043", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("0x43", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("00", &root, false, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader().JsonToValue("043", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("0x43", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("00", false, false));
+  ASSERT_FALSE(root.get());
 
   // Test 0 (which needs to be special cased because of the leading zero
   // clause).
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("0", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("0", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_INTEGER));
   int_val = 1;
   ASSERT_TRUE(root->GetAsInteger(&int_val));
   ASSERT_EQ(0, int_val);
-  delete root;
 
   // Numbers that overflow ints should succeed, being internally promoted to
   // storage as doubles
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("2147483648", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("2147483648", false, false));
+  ASSERT_TRUE(root.get());
   double real_val;
 #ifdef ARCH_CPU_32_BITS
   ASSERT_TRUE(root->IsType(Value::TYPE_REAL));
@@ -76,10 +65,8 @@ TEST(JSONReaderTest, Reading) {
   ASSERT_TRUE(root->GetAsInteger(&int_val));
   ASSERT_EQ(2147483648, int_val);
 #endif
-  delete root;
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("-2147483649", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("-2147483649", false, false));
+  ASSERT_TRUE(root.get());
 #ifdef ARCH_CPU_32_BITS
   ASSERT_TRUE(root->IsType(Value::TYPE_REAL));
   real_val = 0.0;
@@ -91,250 +78,194 @@ TEST(JSONReaderTest, Reading) {
   ASSERT_TRUE(root->GetAsInteger(&int_val));
   ASSERT_EQ(-2147483649, int_val);
 #endif
-  delete root;
 
   // Parse a double
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("43.1", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("43.1", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_REAL));
   real_val = 0.0;
   ASSERT_TRUE(root->GetAsReal(&real_val));
   ASSERT_DOUBLE_EQ(43.1, real_val);
-  delete root;
 
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("4.3e-1", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("4.3e-1", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_REAL));
   real_val = 0.0;
   ASSERT_TRUE(root->GetAsReal(&real_val));
   ASSERT_DOUBLE_EQ(.43, real_val);
-  delete root;
 
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("2.1e0", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("2.1e0", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_REAL));
   real_val = 0.0;
   ASSERT_TRUE(root->GetAsReal(&real_val));
   ASSERT_DOUBLE_EQ(2.1, real_val);
-  delete root;
 
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("2.1e+0001", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("2.1e+0001", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_REAL));
   real_val = 0.0;
   ASSERT_TRUE(root->GetAsReal(&real_val));
   ASSERT_DOUBLE_EQ(21.0, real_val);
-  delete root;
 
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("0.01", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("0.01", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_REAL));
   real_val = 0.0;
   ASSERT_TRUE(root->GetAsReal(&real_val));
   ASSERT_DOUBLE_EQ(0.01, real_val);
-  delete root;
 
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("1.00", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("1.00", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_REAL));
   real_val = 0.0;
   ASSERT_TRUE(root->GetAsReal(&real_val));
   ASSERT_DOUBLE_EQ(1.0, real_val);
-  delete root;
 
   // Fractional parts must have a digit before and after the decimal point.
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("1.", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue(".1", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("1.e10", &root, false, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader().JsonToValue("1.", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue(".1", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("1.e10", false, false));
+  ASSERT_FALSE(root.get());
 
   // Exponent must have a digit following the 'e'.
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("1e", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("1E", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("1e1.", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("1e1.0", &root, false, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader().JsonToValue("1e", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("1E", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("1e1.", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("1e1.0", false, false));
+  ASSERT_FALSE(root.get());
 
   // INF/-INF/NaN are not valid
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("1e1000", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("-1e1000", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("NaN", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("nan", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("inf", &root, false, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader().JsonToValue("1e1000", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("-1e1000", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("NaN", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("nan", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("inf", false, false));
+  ASSERT_FALSE(root.get());
 
   // Invalid number formats
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("4.3.1", &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("4e3.1", &root, false, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader().JsonToValue("4.3.1", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("4e3.1", false, false));
+  ASSERT_FALSE(root.get());
 
   // Test string parser
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("\"hello world\"", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("\"hello world\"", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_STRING));
   std::wstring str_val;
   ASSERT_TRUE(root->GetAsString(&str_val));
   ASSERT_EQ(L"hello world", str_val);
-  delete root;
 
   // Empty string
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("\"\"", &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("\"\"", false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_STRING));
   str_val.clear();
   ASSERT_TRUE(root->GetAsString(&str_val));
   ASSERT_EQ(L"", str_val);
-  delete root;
 
   // Test basic string escapes
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("\" \\\"\\\\\\/\\b\\f\\n\\r\\t\\v\"",
-                                       &root, false, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader().JsonToValue("\" \\\"\\\\\\/\\b\\f\\n\\r\\t\\v\"",
+                                      false, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_STRING));
   str_val.clear();
   ASSERT_TRUE(root->GetAsString(&str_val));
   ASSERT_EQ(L" \"\\/\b\f\n\r\t\v", str_val);
-  delete root;
 
   // Test hex and unicode escapes including the null character.
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("\"\\x41\\x00\\u1234\"", &root, false,
+  root.reset(JSONReader().JsonToValue("\"\\x41\\x00\\u1234\"", false,
                                       false));
-  ASSERT_TRUE(root);
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_STRING));
   str_val.clear();
   ASSERT_TRUE(root->GetAsString(&str_val));
   ASSERT_EQ(std::wstring(L"A\0\x1234", 3), str_val);
-  delete root;
 
   // Test invalid strings
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("\"no closing quote", &root, false,
-                                       false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("\"\\z invalid escape char\"", &root,
-                                       false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("\"\\xAQ invalid hex code\"", &root,
-                                       false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("not enough hex chars\\x1\"", &root,
-                                       false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("\"not enough escape chars\\u123\"",
-                                       &root, false, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("\"extra backslash at end of input\\\"",
-                                       &root, false, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader().JsonToValue("\"no closing quote", false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("\"\\z invalid escape char\"", false,
+                                      false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("\"\\xAQ invalid hex code\"", false,
+                                      false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("not enough hex chars\\x1\"", false,
+                                      false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("\"not enough escape chars\\u123\"",
+                                      false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("\"extra backslash at end of input\\\"",
+                                      false, false));
+  ASSERT_FALSE(root.get());
 
   // Basic array
-  root = NULL;
-  ASSERT_TRUE(JSONReader::Read("[true, false, null]", &root, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader::Read("[true, false, null]", false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_LIST));
-  ListValue* list = static_cast<ListValue*>(root);
+  ListValue* list = static_cast<ListValue*>(root.get());
   ASSERT_EQ(3U, list->GetSize());
 
   // Test with trailing comma.  Should be parsed the same as above.
-  Value* root2 = NULL;
-  ASSERT_TRUE(JSONReader::Read("[true, false, null, ]", &root2, true));
-  EXPECT_TRUE(root->Equals(root2));
-  delete root;
-  delete root2;
+  scoped_ptr<Value> root2;
+  root2.reset(JSONReader::Read("[true, false, null, ]", true));
+  EXPECT_TRUE(root->Equals(root2.get()));
 
   // Empty array
-  root = NULL;
-  ASSERT_TRUE(JSONReader::Read("[]", &root, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader::Read("[]", false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_LIST));
-  list = static_cast<ListValue*>(root);
+  list = static_cast<ListValue*>(root.get());
   ASSERT_EQ(0U, list->GetSize());
-  delete root;
 
   // Nested arrays
-  root = NULL;
-  ASSERT_TRUE(JSONReader::Read("[[true], [], [false, [], [null]], null]", &root,
-                               false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader::Read("[[true], [], [false, [], [null]], null]",
+                              false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_LIST));
-  list = static_cast<ListValue*>(root);
+  list = static_cast<ListValue*>(root.get());
   ASSERT_EQ(4U, list->GetSize());
 
   // Lots of trailing commas.
-  root2 = NULL;
-  ASSERT_TRUE(JSONReader::Read("[[true], [], [false, [], [null, ]  , ], null,]",
-                               &root2, true));
-  EXPECT_TRUE(root->Equals(root2));
-  delete root;
-  delete root2;
+  root2.reset(JSONReader::Read("[[true], [], [false, [], [null, ]  , ], null,]",
+                               true));
+  EXPECT_TRUE(root->Equals(root2.get()));
 
   // Invalid, missing close brace.
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("[[true], [], [false, [], [null]], null", &root,
-                                false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("[[true], [], [false, [], [null]], null", false));
+  ASSERT_FALSE(root.get());
 
   // Invalid, too many commas
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("[true,, null]", &root, false));
-  ASSERT_FALSE(root);
-  ASSERT_FALSE(JSONReader::Read("[true,, null]", &root, true));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("[true,, null]", false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("[true,, null]", true));
+  ASSERT_FALSE(root.get());
 
   // Invalid, no commas
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("[true null]", &root, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("[true null]", false));
+  ASSERT_FALSE(root.get());
 
   // Invalid, trailing comma
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("[true,]", &root, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("[true,]", false));
+  ASSERT_FALSE(root.get());
 
   // Valid if we set |allow_trailing_comma| to true.
-  EXPECT_TRUE(JSONReader::Read("[true,]", &root, true));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader::Read("[true,]", true));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_LIST));
-  list = static_cast<ListValue*>(root);
+  list = static_cast<ListValue*>(root.get());
   EXPECT_EQ(1U, list->GetSize());
   Value* tmp_value = NULL;
   ASSERT_TRUE(list->Get(0, &tmp_value));
@@ -342,34 +273,29 @@ TEST(JSONReaderTest, Reading) {
   bool bool_value = false;
   ASSERT_TRUE(tmp_value->GetAsBoolean(&bool_value));
   EXPECT_TRUE(bool_value);
-  delete root;
 
   // Don't allow empty elements, even if |allow_trailing_comma| is
   // true.
-  root = NULL;
-  EXPECT_FALSE(JSONReader::Read("[,]", &root, true));
-  EXPECT_FALSE(root);
-  EXPECT_FALSE(JSONReader::Read("[true,,]", &root, true));
-  EXPECT_FALSE(root);
-  EXPECT_FALSE(JSONReader::Read("[,true,]", &root, true));
-  EXPECT_FALSE(root);
-  EXPECT_FALSE(JSONReader::Read("[true,,false]", &root, true));
-  EXPECT_FALSE(root);
+  root.reset(JSONReader::Read("[,]", true));
+  EXPECT_FALSE(root.get());
+  root.reset(JSONReader::Read("[true,,]", true));
+  EXPECT_FALSE(root.get());
+  root.reset(JSONReader::Read("[,true,]", true));
+  EXPECT_FALSE(root.get());
+  root.reset(JSONReader::Read("[true,,false]", true));
+  EXPECT_FALSE(root.get());
 
   // Test objects
-  root = NULL;
-  ASSERT_TRUE(JSONReader::Read("{}", &root, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader::Read("{}", false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_DICTIONARY));
-  delete root;
 
-  root = NULL;
-  ASSERT_TRUE(JSONReader::Read(
-    "{\"number\":9.87654321, \"null\":null , \"\\x53\" : \"str\" }", &root,
+  root.reset(JSONReader::Read(
+    "{\"number\":9.87654321, \"null\":null , \"\\x53\" : \"str\" }",
     false));
-  ASSERT_TRUE(root);
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_DICTIONARY));
-  DictionaryValue* dict_val = static_cast<DictionaryValue*>(root);
+  DictionaryValue* dict_val = static_cast<DictionaryValue*>(root.get());
   real_val = 0.0;
   ASSERT_TRUE(dict_val->GetReal(L"number", &real_val));
   ASSERT_DOUBLE_EQ(9.87654321, real_val);
@@ -380,21 +306,16 @@ TEST(JSONReaderTest, Reading) {
   ASSERT_TRUE(dict_val->GetString(L"S", &str_val));
   ASSERT_EQ(L"str", str_val);
 
-  root2 = NULL;
-  ASSERT_TRUE(JSONReader::Read(
-    "{\"number\":9.87654321, \"null\":null , \"\\x53\" : \"str\", }", &root2,
-    true));
-  EXPECT_TRUE(root->Equals(root2));
-  delete root;
-  delete root2;
+  root2.reset(JSONReader::Read(
+    "{\"number\":9.87654321, \"null\":null , \"\\x53\" : \"str\", }", true));
+  EXPECT_TRUE(root->Equals(root2.get()));
 
   // Test nesting
-  root = NULL;
-  ASSERT_TRUE(JSONReader::Read(
-    "{\"inner\":{\"array\":[true]},\"false\":false,\"d\":{}}", &root, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader::Read(
+    "{\"inner\":{\"array\":[true]},\"false\":false,\"d\":{}}", false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_DICTIONARY));
-  dict_val = static_cast<DictionaryValue*>(root);
+  dict_val = static_cast<DictionaryValue*>(root.get());
   DictionaryValue* inner_dict = NULL;
   ASSERT_TRUE(dict_val->GetDictionary(L"inner", &inner_dict));
   ListValue* inner_array = NULL;
@@ -406,61 +327,49 @@ TEST(JSONReaderTest, Reading) {
   inner_dict = NULL;
   ASSERT_TRUE(dict_val->GetDictionary(L"d", &inner_dict));
 
-  root2 = NULL;
-  ASSERT_TRUE(JSONReader::Read(
-    "{\"inner\": {\"array\":[true] , },\"false\":false,\"d\":{},}", &root2,
-    true));
-  EXPECT_TRUE(root->Equals(root2));
-  delete root;
-  delete root2;
+  root2.reset(JSONReader::Read(
+    "{\"inner\": {\"array\":[true] , },\"false\":false,\"d\":{},}", true));
+  EXPECT_TRUE(root->Equals(root2.get()));
 
   // Invalid, no closing brace
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("{\"a\": true", &root, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("{\"a\": true", false));
+  ASSERT_FALSE(root.get());
 
   // Invalid, keys must be quoted
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("{foo:true}", &root, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("{foo:true}", false));
+  ASSERT_FALSE(root.get());
 
   // Invalid, trailing comma
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("{\"a\":true,}", &root, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("{\"a\":true,}", false));
+  ASSERT_FALSE(root.get());
 
   // Invalid, too many commas
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("{\"a\":true,,\"b\":false}", &root, false));
-  ASSERT_FALSE(root);
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("{\"a\":true,,\"b\":false}", &root, true));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("{\"a\":true,,\"b\":false}", false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("{\"a\":true,,\"b\":false}", true));
+  ASSERT_FALSE(root.get());
 
   // Invalid, no separator
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("{\"a\" \"b\"}", &root, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("{\"a\" \"b\"}", false));
+  ASSERT_FALSE(root.get());
 
   // Invalid, lone comma.
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("{,}", &root, false));
-  ASSERT_FALSE(root);
-  ASSERT_FALSE(JSONReader::Read("{,}", &root, true));
-  ASSERT_FALSE(root);
-  ASSERT_FALSE(JSONReader::Read("{\"a\":true,,}", &root, true));
-  ASSERT_FALSE(root);
-  ASSERT_FALSE(JSONReader::Read("{,\"a\":true}", &root, true));
-  ASSERT_FALSE(root);
-  ASSERT_FALSE(JSONReader::Read("{\"a\":true,,\"b\":false}", &root, true));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read("{,}", false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("{,}", true));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("{\"a\":true,,}", true));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("{,\"a\":true}", true));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("{\"a\":true,,\"b\":false}", true));
+  ASSERT_FALSE(root.get());
 
   // Test stack overflow
-  root = NULL;
   std::string evil(1000000, '[');
   evil.append(std::string(1000000, ']'));
-  ASSERT_FALSE(JSONReader::Read(evil, &root, false));
-  ASSERT_FALSE(root);
+  root.reset(JSONReader::Read(evil, false));
+  ASSERT_FALSE(root.get());
 
   // A few thousand adjacent lists is fine.
   std::string not_evil("[");
@@ -469,58 +378,58 @@ TEST(JSONReaderTest, Reading) {
     not_evil.append("[],");
   }
   not_evil.append("[]]");
-  ASSERT_TRUE(JSONReader::Read(not_evil, &root, false));
-  ASSERT_TRUE(root);
+  root.reset(JSONReader::Read(not_evil, false));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_LIST));
-  list = static_cast<ListValue*>(root);
+  list = static_cast<ListValue*>(root.get());
   ASSERT_EQ(5001U, list->GetSize());
-  delete root;
 
   // Test utf8 encoded input
-  root = NULL;
-  ASSERT_TRUE(JSONReader().JsonToValue("\"\xe7\xbd\x91\xe9\xa1\xb5\"", &root,
+  root.reset(JSONReader().JsonToValue("\"\xe7\xbd\x91\xe9\xa1\xb5\"",
                                       false, false));
-  ASSERT_TRUE(root);
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_STRING));
   str_val.clear();
   ASSERT_TRUE(root->GetAsString(&str_val));
   ASSERT_EQ(L"\x7f51\x9875", str_val);
-  delete root;
 
   // Test invalid utf8 encoded input
-  root = NULL;
-  ASSERT_FALSE(JSONReader().JsonToValue("\"345\xb0\xa1\xb0\xa2\"", &root,
-                                       false, false));
-  ASSERT_FALSE(JSONReader().JsonToValue("\"123\xc0\x81\"", &root,
-                                       false, false));
+  root.reset(JSONReader().JsonToValue("\"345\xb0\xa1\xb0\xa2\"",
+                                      false, false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader().JsonToValue("\"123\xc0\x81\"",
+                                      false, false));
+  ASSERT_FALSE(root.get());
 
   // Test invalid root objects.
-  root = NULL;
-  ASSERT_FALSE(JSONReader::Read("null", &root, false));
-  ASSERT_FALSE(JSONReader::Read("true", &root, false));
-  ASSERT_FALSE(JSONReader::Read("10", &root, false));
-  ASSERT_FALSE(JSONReader::Read("\"root\"", &root, false));
+  root.reset(JSONReader::Read("null", false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("true", false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("10", false));
+  ASSERT_FALSE(root.get());
+  root.reset(JSONReader::Read("\"root\"", false));
+  ASSERT_FALSE(root.get());
 }
 
 TEST(JSONReaderTest, ErrorMessages) {
   // Error strings should not be modified in case of success.
   std::string error_message;
-  Value* root = NULL;
-  EXPECT_TRUE(JSONReader::ReadAndReturnError("[42]", &root, false,
-                                             &error_message));
+  scoped_ptr<Value> root;
+  root.reset(JSONReader::ReadAndReturnError("[42]", false, &error_message));
   EXPECT_TRUE(error_message.empty());
 
   // Test line and column counting
   const char* big_json = "[\n0,\n1,\n2,\n3,4,5,6 7,\n8,\n9\n]";
   // error here --------------------------------^
-  EXPECT_FALSE(JSONReader::ReadAndReturnError(big_json, &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError(big_json, false, &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(5, 9, JSONReader::kSyntaxError),
             error_message);
 
   // Test each of the error conditions
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("{},{}", &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError("{},{}", false, &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 3,
       JSONReader::kUnexpectedDataAfterRoot), error_message);
 
@@ -529,50 +438,55 @@ TEST(JSONReaderTest, ErrorMessages) {
     nested_json.insert(nested_json.begin(), '[');
     nested_json.append(1, ']');
   }
-  EXPECT_FALSE(JSONReader::ReadAndReturnError(nested_json, &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError(nested_json, false,
+                                            &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 101, JSONReader::kTooMuchNesting),
             error_message);
 
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("42", &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError("42", false, &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 1,
       JSONReader::kBadRootElementType), error_message);
 
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("[1,]", &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError("[1,]", false, &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 4, JSONReader::kTrailingComma),
             error_message);
 
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("{foo:\"bar\"}", &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError("{foo:\"bar\"}", false,
+                                            &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 2,
       JSONReader::kUnquotedDictionaryKey), error_message);
 
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("{\"foo\":\"bar\",}", &root,
-                                              false, &error_message));
+  root.reset(JSONReader::ReadAndReturnError("{\"foo\":\"bar\",}", false,
+                                            &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 14, JSONReader::kTrailingComma),
             error_message);
 
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("[nu]", &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError("[nu]", false, &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 2, JSONReader::kSyntaxError),
             error_message);
 
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("[\"xxx\\xq\"]", &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError("[\"xxx\\xq\"]", false,
+                                            &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 7, JSONReader::kInvalidEscape),
             error_message);
 
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("[\"xxx\\uq\"]", &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError("[\"xxx\\uq\"]", false,
+                                            &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 7, JSONReader::kInvalidEscape),
             error_message);
 
-  EXPECT_FALSE(JSONReader::ReadAndReturnError("[\"xxx\\q\"]", &root, false,
-                                              &error_message));
+  root.reset(JSONReader::ReadAndReturnError("[\"xxx\\q\"]", false,
+                                            &error_message));
+  EXPECT_FALSE(root.get());
   EXPECT_EQ(JSONReader::FormatErrorMessage(1, 7, JSONReader::kInvalidEscape),
             error_message);
 
-  delete root;
 }
diff --git a/base/values.h b/base/values.h
index 2f28f11..ebd2117 100644
--- a/base/values.h
+++ b/base/values.h
@@ -358,13 +358,10 @@ class ValueSerializer {
   virtual bool Serialize(const Value& root) = 0;
 
   // This method deserializes the subclass-specific format into a Value object.
-  // The method should return true if and only if the root parameter is set
-  // to a complete Value representation of the serialized form.  If the
-  // return value is true, the caller takes ownership of the objects pointed
-  // to by root.  If the return value is false, root should be unchanged and if
-  // error_message is non-null, it should be filled with a message describing
-  // the error.
-  virtual bool Deserialize(Value** root, std::string* error_message) = 0;
+  // If the return value is non-NULL, the caller takes ownership of returned
+  // Value. If the return value is NULL, and if error_message is non-NULL,
+  // error_message should be filled with a message describing the error.
+  virtual Value* Deserialize(std::string* error_message) = 0;
 };
 
 #endif  // BASE_VALUES_H_