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

17 files changed, 121 insertions, 149 deletions

diff --git a/chrome/browser/autocomplete/search_provider.cc b/chrome/browser/autocomplete/search_provider.cc
index 32c2fb2..17bdcc8 100644
--- a/chrome/browser/autocomplete/search_provider.cc
+++ b/chrome/browser/autocomplete/search_provider.cc
@@ -129,13 +129,14 @@ void SearchProvider::OnURLFetchComplete(const URLFetcher* source,
     }
   }
 
-  JSONStringValueSerializer deserializer(json_data);
-  deserializer.set_allow_trailing_comma(true);
-  Value* root_val = NULL;
-  have_suggest_results_ = status.is_success() && (response_code == 200) &&
-      deserializer.Deserialize(&root_val, NULL) &&
-      ParseSuggestResults(root_val);
-  delete root_val;
+  if (status.is_success() && response_code == 200) {
+    JSONStringValueSerializer deserializer(json_data);
+    deserializer.set_allow_trailing_comma(true);
+    scoped_ptr<Value> root_val(deserializer.Deserialize(NULL));
+    have_suggest_results_ =
+        root_val.get() && ParseSuggestResults(root_val.get());
+  }
+
   ConvertResultsToAutocompleteMatches();
   listener_->OnProviderUpdate(!suggest_results_.empty());
 }
diff --git a/chrome/browser/bookmarks/bookmark_storage.cc b/chrome/browser/bookmarks/bookmark_storage.cc
index e6e9a50..23f47b4 100644
--- a/chrome/browser/bookmarks/bookmark_storage.cc
+++ b/chrome/browser/bookmarks/bookmark_storage.cc
@@ -167,7 +167,7 @@ void BookmarkStorageBackend::Read(scoped_refptr<BookmarkStorage> service,
   Value* root = NULL;
   if (bookmark_file_exists) {
     JSONFileValueSerializer serializer(path);
-    serializer.Deserialize(&root, NULL);
+    root = serializer.Deserialize(NULL);
   }
 
   // BookmarkStorage takes ownership of root.
diff --git a/chrome/browser/debugger/debugger_host_impl.cpp b/chrome/browser/debugger/debugger_host_impl.cpp
index c2eb41d..32c13fd 100644
--- a/chrome/browser/debugger/debugger_host_impl.cpp
+++ b/chrome/browser/debugger/debugger_host_impl.cpp
@@ -83,8 +83,8 @@ void DebuggerHostImpl::Debug(TabContents* tab) {
 
 void DebuggerHostImpl::DebugMessage(const std::wstring& msg) {
 
-  Value* msg_value = NULL;
-  if (!JSONReader::Read(WideToUTF8(msg), &msg_value, false)) {
+  Value* msg_value = JSONReader::Read(WideToUTF8(msg), false);
+  if (!msg_value) {
     msg_value = Value::CreateStringValue(L"Message parse error!");
   }
   ListValue* argv = new ListValue;
diff --git a/chrome/browser/dom_ui/dom_ui.cc b/chrome/browser/dom_ui/dom_ui.cc
index 4fe9070..e7f2765 100644
--- a/chrome/browser/dom_ui/dom_ui.cc
+++ b/chrome/browser/dom_ui/dom_ui.cc
@@ -31,9 +31,10 @@ void DOMUI::ProcessDOMUIMessage(const std::string& message,
     return;
 
   // Convert the content JSON into a Value.
-  Value* value = NULL;
+  scoped_ptr<Value> value;
   if (!content.empty()) {
-    if (!JSONReader::Read(content, &value, false)) {
+    value.reset(JSONReader::Read(content, false));
+    if (!value.get()) {
       // The page sent us something that we didn't understand.
       // This probably indicates a programming error.
       NOTREACHED();
@@ -42,8 +43,7 @@ void DOMUI::ProcessDOMUIMessage(const std::string& message,
   }
 
   // Forward this message and content on.
-  callback->second->Run(value);
-  delete value;
+  callback->second->Run(value.get());
 }
 
 void DOMUI::CallJavascriptFunction(const std::wstring& function_name,
diff --git a/chrome/browser/dom_ui/dom_ui_host.cc b/chrome/browser/dom_ui/dom_ui_host.cc
index d9d0333..ff2ca1e 100644
--- a/chrome/browser/dom_ui/dom_ui_host.cc
+++ b/chrome/browser/dom_ui/dom_ui_host.cc
@@ -78,9 +78,10 @@ void DOMUIHost::ProcessDOMUIMessage(const std::string& message,
     return;
 
   // Convert the content JSON into a Value.
-  Value* value = NULL;
+  scoped_ptr<Value> value;
   if (!content.empty()) {
-    if (!JSONReader::Read(content, &value, false)) {
+    value.reset(JSONReader::Read(content, false));
+    if (!value.get()) {
       // The page sent us something that we didn't understand.
       // This probably indicates a programming error.
       NOTREACHED();
@@ -89,8 +90,7 @@ void DOMUIHost::ProcessDOMUIMessage(const std::string& message,
   }
 
   // Forward this message and content on.
-  callback->second->Run(value);
-  delete value;
+  callback->second->Run(value.get());
 }
 
 WebPreferences DOMUIHost::GetWebkitPrefs() {
diff --git a/chrome/browser/extensions/extensions_service.cc b/chrome/browser/extensions/extensions_service.cc
index cd0397c..f38ff04 100644
--- a/chrome/browser/extensions/extensions_service.cc
+++ b/chrome/browser/extensions/extensions_service.cc
@@ -88,15 +88,14 @@ bool ExtensionsServiceBackend::LoadExtensionsFromDirectory(
     }
 
     JSONFileValueSerializer serializer(manifest_path.ToWStringHack());
-    Value* root = NULL;
     std::string error;
-    if (!serializer.Deserialize(&root, &error)) {
+    scoped_ptr<Value> root(serializer.Deserialize(&error));
+    if (!root.get()) {
       ReportExtensionLoadError(frontend.get(), child_path.ToWStringHack(),
                                error);
       continue;
     }
 
-    scoped_ptr<Value> scoped_root(root);
     if (!root->IsType(Value::TYPE_DICTIONARY)) {
       ReportExtensionLoadError(frontend.get(), child_path.ToWStringHack(),
                                Extension::kInvalidManifestError);
@@ -104,7 +103,7 @@ bool ExtensionsServiceBackend::LoadExtensionsFromDirectory(
     }
 
     scoped_ptr<Extension> extension(new Extension(child_path));
-    if (!extension->InitFromValue(*static_cast<DictionaryValue*>(root),
+    if (!extension->InitFromValue(*static_cast<DictionaryValue*>(root.get()),
                                   &error)) {
       ReportExtensionLoadError(frontend.get(), child_path.ToWStringHack(),
                                error);
diff --git a/chrome/browser/page_state.cc b/chrome/browser/page_state.cc
index f47a4cf..1d52ffb 100644
--- a/chrome/browser/page_state.cc
+++ b/chrome/browser/page_state.cc
@@ -40,16 +40,15 @@ void PageState::InitWithBytes(const std::string& bytes) {
   state_.reset(new DictionaryValue);
 
   JSONStringValueSerializer serializer(bytes);
-  Value* root = NULL;
+  scoped_ptr<Value> root(serializer.Deserialize(NULL));
 
-  if (!serializer.Deserialize(&root, NULL))
+  if (!root.get()) {
     NOTREACHED();
-
-  if (root != NULL && root->GetType() == Value::TYPE_DICTIONARY) {
-    state_.reset(static_cast<DictionaryValue*>(root));
-  } else if (root) {
-    delete root;
+    return;
   }
+
+  if (root->GetType() == Value::TYPE_DICTIONARY)
+    state_.reset(static_cast<DictionaryValue*>(root.release()));
 }
 
 void PageState::GetByteRepresentation(std::string* out) const {
diff --git a/chrome/common/json_value_serializer.cc b/chrome/common/json_value_serializer.cc
index 82938ec..54afe7a 100644
--- a/chrome/common/json_value_serializer.cc
+++ b/chrome/common/json_value_serializer.cc
@@ -21,13 +21,11 @@ bool JSONStringValueSerializer::Serialize(const Value& root) {
   return true;
 }
 
-bool JSONStringValueSerializer::Deserialize(Value** root,
-                                            std::string* error_message) {
+Value* JSONStringValueSerializer::Deserialize(std::string* error_message) {
   if (!json_string_)
     return false;
 
-  return JSONReader::ReadAndReturnError(*json_string_, root,
-                                        allow_trailing_comma_,
+  return JSONReader::ReadAndReturnError(*json_string_, allow_trailing_comma_,
                                         error_message);
 }
 
@@ -50,13 +48,12 @@ bool JSONFileValueSerializer::Serialize(const Value& root) {
   return true;
 }
 
-bool JSONFileValueSerializer::Deserialize(Value** root,
-                                          std::string* error_message) {
+Value* JSONFileValueSerializer::Deserialize(std::string* error_message) {
   std::string json_string;
   if (!file_util::ReadFileToString(json_file_path_, &json_string)) {
     return false;
   }
   JSONStringValueSerializer serializer(json_string);
-  return serializer.Deserialize(root, error_message);
+  return serializer.Deserialize(error_message);
 }
 
diff --git a/chrome/common/json_value_serializer.h b/chrome/common/json_value_serializer.h
index 2e581ee..7a51528 100644
--- a/chrome/common/json_value_serializer.h
+++ b/chrome/common/json_value_serializer.h
@@ -39,12 +39,9 @@ class JSONStringValueSerializer : public ValueSerializer {
 
   // Attempt to deserialize the data structure encoded in the string passed
   // in to the constructor into a structure of Value objects.  If the return
-  // value is true, the |root| parameter will be set to point to a new Value
-  // object that corresponds to the values represented in the string.  The
-  // caller takes ownership of the returned Value objects. Otherwise, the root
-  // value will be changed and if |error_message| is non-null, it will contain
+  // value is NULL and |error_message| is non-null, |error-message| will contain
   // a string describing the error.
-  bool Deserialize(Value** root, std::string* error_message);
+  Value* Deserialize(std::string* error_message);
 
   void set_pretty_print(bool new_value) { pretty_print_ = new_value; }
   bool pretty_print() { return pretty_print_; }
@@ -86,12 +83,9 @@ class JSONFileValueSerializer : public ValueSerializer {
 
   // 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 true, the |root| parameter will be set to point to a new Value
-  // object that corresponds to the values represented in the file.  The
-  // caller takes ownership of the returned Value objects. Otherwise, the root
-  // value will be changed and if |error_message| is non-null, it will contain
-  // a string describing the error.
-  bool Deserialize(Value** root, std::string* error_message);
+  // value is NULL, and if |error_message| is non-null, |error_message| will
+  // contain a string describing the error.
+  Value* Deserialize(std::string* error_message);
 
  private:
   std::wstring json_file_path_;
diff --git a/chrome/common/json_value_serializer_perftest.cc b/chrome/common/json_value_serializer_perftest.cc
index 6570d34..bef8fbe 100644
--- a/chrome/common/json_value_serializer_perftest.cc
+++ b/chrome/common/json_value_serializer_perftest.cc
@@ -52,10 +52,9 @@ TEST_F(JSONValueSerializerTests, Reading) {
   PerfTimeLogger chrome_timer("chrome");
   for (int i = 0; i < kIterations; ++i) {
     for (size_t j = 0; j < test_cases_.size(); ++j) {
-      Value* root = NULL;
       JSONStringValueSerializer reader(test_cases_[j]);
-      ASSERT_TRUE(reader.Deserialize(&root, NULL));
-      delete root;
+      scoped_ptr<Value> root(reader.Deserialize(NULL));
+      ASSERT_TRUE(root.get());
     }
   }
   chrome_timer.Done();
@@ -67,9 +66,9 @@ TEST_F(JSONValueSerializerTests, CompactWriting) {
   // Convert test cases to Value objects.
   std::vector<Value*> test_cases;
   for (size_t i = 0; i < test_cases_.size(); ++i) {
-    Value* root = NULL;
     JSONStringValueSerializer reader(test_cases_[i]);
-    ASSERT_TRUE(reader.Deserialize(&root, NULL));
+    Value* root = reader.Deserialize(NULL);
+    ASSERT_TRUE(root);
     test_cases.push_back(root);
   }
 
diff --git a/chrome/common/json_value_serializer_unittest.cc b/chrome/common/json_value_serializer_unittest.cc
index 3dd175b..30f6320 100644
--- a/chrome/common/json_value_serializer_unittest.cc
+++ b/chrome/common/json_value_serializer_unittest.cc
@@ -16,13 +16,12 @@
 TEST(JSONValueSerializerTest, Roundtrip) {
   const std::string original_serialization =
     "{\"bool\":true,\"int\":42,\"list\":[1,2],\"null\":null,\"real\":3.14}";
-  Value* root = NULL;
   JSONStringValueSerializer serializer(original_serialization);
-  ASSERT_TRUE(serializer.Deserialize(&root, NULL));
-  ASSERT_TRUE(root);
+  scoped_ptr<Value> root(serializer.Deserialize(NULL));
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_DICTIONARY));
 
-  DictionaryValue* root_dict = static_cast<DictionaryValue*>(root);
+  DictionaryValue* root_dict = static_cast<DictionaryValue*>(root.get());
 
   Value* null_value = NULL;
   ASSERT_TRUE(root_dict->Get(L"null", &null_value));
@@ -61,8 +60,6 @@ TEST(JSONValueSerializerTest, Roundtrip) {
     "   \"real\": 3.14\r\n"
     "}\r\n";
   ASSERT_EQ(pretty_serialization, test_serialization);
-
-  delete root;
 }
 
 TEST(JSONValueSerializerTest, StringEscape) {
@@ -119,14 +116,14 @@ TEST(JSONValueSerializerTest, UnicodeStrings) {
   ASSERT_EQ(expected, actual);
 
   // escaped ascii text -> json
-  Value* deserial_root = NULL;
   JSONStringValueSerializer deserializer(expected);
-  ASSERT_TRUE(deserializer.Deserialize(&deserial_root, NULL));
-  DictionaryValue* dict_root = static_cast<DictionaryValue*>(deserial_root);
+  scoped_ptr<Value> deserial_root(deserializer.Deserialize(NULL));
+  ASSERT_TRUE(deserial_root.get());
+  DictionaryValue* dict_root =
+      static_cast<DictionaryValue*>(deserial_root.get());
   std::wstring web_value;
   ASSERT_TRUE(dict_root->GetString(L"web", &web_value));
   ASSERT_EQ(test, web_value);
-  delete deserial_root;
 }
 
 TEST(JSONValueSerializerTest, HexStrings) {
@@ -143,57 +140,53 @@ TEST(JSONValueSerializerTest, HexStrings) {
   ASSERT_EQ(expected, actual);
 
   // escaped ascii text -> json
-  Value* deserial_root = NULL;
   JSONStringValueSerializer deserializer(expected);
-  ASSERT_TRUE(deserializer.Deserialize(&deserial_root, NULL));
-  DictionaryValue* dict_root = static_cast<DictionaryValue*>(deserial_root);
+  scoped_ptr<Value> deserial_root(deserializer.Deserialize(NULL));
+  ASSERT_TRUE(deserial_root.get());
+  DictionaryValue* dict_root =
+      static_cast<DictionaryValue*>(deserial_root.get());
   std::wstring test_value;
   ASSERT_TRUE(dict_root->GetString(L"test", &test_value));
   ASSERT_EQ(test, test_value);
-  delete deserial_root;
 
   // Test converting escaped regular chars
-  deserial_root = NULL;
   std::string escaped_chars = "{\"test\":\"\\x67\\x6f\"}";
   JSONStringValueSerializer deserializer2(escaped_chars);
-  ASSERT_TRUE(deserializer2.Deserialize(&deserial_root, NULL));
-  dict_root = static_cast<DictionaryValue*>(deserial_root);
+  deserial_root.reset(deserializer2.Deserialize(NULL));
+  ASSERT_TRUE(deserial_root.get());
+  dict_root = static_cast<DictionaryValue*>(deserial_root.get());
   ASSERT_TRUE(dict_root->GetString(L"test", &test_value));
   ASSERT_EQ(std::wstring(L"go"), test_value);
-  delete deserial_root;
 }
 
 TEST(JSONValueSerializerTest, AllowTrailingComma) {
-  Value* root = NULL;
-  Value* root_expected = NULL;
+  scoped_ptr<Value> root;
+  scoped_ptr<Value> root_expected;
   std::string test_with_commas("{\"key\": [true,],}");
   std::string test_no_commas("{\"key\": [true]}");
 
   JSONStringValueSerializer serializer(test_with_commas);
   serializer.set_allow_trailing_comma(true);
   JSONStringValueSerializer serializer_expected(test_no_commas);
-  ASSERT_TRUE(serializer.Deserialize(&root, NULL));
-  ASSERT_TRUE(serializer_expected.Deserialize(&root_expected, NULL));
-  ASSERT_TRUE(root->Equals(root_expected));
-
-  delete root;
-  delete root_expected;
+  root.reset(serializer.Deserialize(NULL));
+  ASSERT_TRUE(root.get());
+  root_expected.reset(serializer_expected.Deserialize(NULL));
+  ASSERT_TRUE(root_expected.get());
+  ASSERT_TRUE(root->Equals(root_expected.get()));
 }
 
 namespace {
 
 void ValidateJsonList(const std::string& json) {
-  Value* root = NULL;
-  ASSERT_TRUE(JSONReader::Read(json, &root, false));
-  ASSERT_TRUE(root && root->IsType(Value::TYPE_LIST));
-  ListValue* list = static_cast<ListValue*>(root);
+  scoped_ptr<Value> root(JSONReader::Read(json, false));
+  ASSERT_TRUE(root.get() && root->IsType(Value::TYPE_LIST));
+  ListValue* list = static_cast<ListValue*>(root.get());
   ASSERT_EQ(1U, list->GetSize());
   Value* elt = NULL;
   ASSERT_TRUE(list->Get(0, &elt));
   int value = 0;
   ASSERT_TRUE(elt && elt->GetAsInteger(&value));
   ASSERT_EQ(1, value);
-  delete root;
 }
 
 }  // namespace
@@ -206,25 +199,26 @@ TEST(JSONValueSerializerTest, JSONReaderComments) {
   ValidateJsonList("[ 1 /* one */ ] /* end */");
   ValidateJsonList("[ 1 //// ,2\r\n ]");
 
-  Value* root = NULL;
+  scoped_ptr<Value> root;
+
   // It's ok to have a comment in a string.
-  ASSERT_TRUE(JSONReader::Read("[\"// ok\\n /* foo */ \"]", &root, false));
-  ASSERT_TRUE(root && root->IsType(Value::TYPE_LIST));
-  ListValue* list = static_cast<ListValue*>(root);
+  root.reset(JSONReader::Read("[\"// ok\\n /* foo */ \"]", false));
+  ASSERT_TRUE(root.get() && root->IsType(Value::TYPE_LIST));
+  ListValue* list = static_cast<ListValue*>(root.get());
   ASSERT_EQ(1U, list->GetSize());
   Value* elt = NULL;
   ASSERT_TRUE(list->Get(0, &elt));
   std::wstring value;
   ASSERT_TRUE(elt && elt->GetAsString(&value));
   ASSERT_EQ(L"// ok\n /* foo */ ", value);
-  delete root;
 
-  root = NULL;
   // You can't nest comments.
-  ASSERT_FALSE(JSONReader::Read("/* /* inner */ outer */ [ 1 ]", &root, false));
+  root.reset(JSONReader::Read("/* /* inner */ outer */ [ 1 ]", false));
+  ASSERT_FALSE(root.get());
 
   // Not a open comment token.
-  ASSERT_FALSE(JSONReader::Read("/ * * / [1]", &root, false));
+  root.reset(JSONReader::Read("/ * * / [1]", false));
+  ASSERT_FALSE(root.get());
 }
 
 namespace {
@@ -261,13 +255,13 @@ TEST_F(JSONFileValueSerializerTest, Roundtrip) {
   ASSERT_TRUE(file_util::PathExists(original_file_path));
 
   JSONFileValueSerializer deserializer(original_file_path);
-  Value* root;
-  ASSERT_TRUE(deserializer.Deserialize(&root, NULL));
+  scoped_ptr<Value> root;
+  root.reset(deserializer.Deserialize(NULL));
 
-  ASSERT_TRUE(root);
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_DICTIONARY));
 
-  DictionaryValue* root_dict = static_cast<DictionaryValue*>(root);
+  DictionaryValue* root_dict = static_cast<DictionaryValue*>(root.get());
 
   Value* null_value = NULL;
   ASSERT_TRUE(root_dict->Get(L"null", &null_value));
@@ -298,8 +292,6 @@ TEST_F(JSONFileValueSerializerTest, Roundtrip) {
   // Now compare file contents.
   EXPECT_TRUE(file_util::ContentsEqual(original_file_path, written_file_path));
   EXPECT_TRUE(file_util::Delete(written_file_path, false));
-
-  delete root;
 }
 
 TEST_F(JSONFileValueSerializerTest, RoundtripNested) {
@@ -311,8 +303,9 @@ TEST_F(JSONFileValueSerializerTest, RoundtripNested) {
   ASSERT_TRUE(file_util::PathExists(original_file_path));
 
   JSONFileValueSerializer deserializer(original_file_path);
-  Value* root;
-  ASSERT_TRUE(deserializer.Deserialize(&root, NULL));
+  scoped_ptr<Value> root;
+  root.reset(deserializer.Deserialize(NULL));
+  ASSERT_TRUE(root.get());
 
   // Now try writing.
   std::wstring written_file_path = test_dir_;
@@ -326,8 +319,6 @@ TEST_F(JSONFileValueSerializerTest, RoundtripNested) {
   // Now compare file contents.
   EXPECT_TRUE(file_util::ContentsEqual(original_file_path, written_file_path));
   EXPECT_TRUE(file_util::Delete(written_file_path, false));
-
-  delete root;
 }
 
 TEST_F(JSONFileValueSerializerTest, NoWhitespace) {
@@ -337,9 +328,8 @@ TEST_F(JSONFileValueSerializerTest, NoWhitespace) {
                           L"serializer_test_nowhitespace.js");
   ASSERT_TRUE(file_util::PathExists(source_file_path));
   JSONFileValueSerializer serializer(source_file_path);
-  Value* root;
-  ASSERT_TRUE(serializer.Deserialize(&root, NULL));
-  ASSERT_TRUE(root);
-  delete root;
+  scoped_ptr<Value> root;
+  root.reset(serializer.Deserialize(NULL));
+  ASSERT_TRUE(root.get());
 }
 #endif  // defined(OS_WIN)
diff --git a/chrome/common/pref_service.cc b/chrome/common/pref_service.cc
index 8f3322a..870e79e 100644
--- a/chrome/common/pref_service.cc
+++ b/chrome/common/pref_service.cc
@@ -136,38 +136,34 @@ bool PrefService::LoadPersistentPrefs(const std::wstring& file_path) {
   DCHECK(CalledOnValidThread());
 
   JSONFileValueSerializer serializer(file_path);
-  Value* root = NULL;
-  if (serializer.Deserialize(&root, NULL)) {
-    // Preferences should always have a dictionary root.
-    if (!root->IsType(Value::TYPE_DICTIONARY)) {
-      delete root;
-      return false;
-    }
+  scoped_ptr<Value> root(serializer.Deserialize(NULL));
+  if (!root.get())
+    return false;
 
-    persistent_.reset(static_cast<DictionaryValue*>(root));
-    return true;
-  }
+  // Preferences should always have a dictionary root.
+  if (!root->IsType(Value::TYPE_DICTIONARY))
+    return false;
 
-  return false;
+  persistent_.reset(static_cast<DictionaryValue*>(root.release()));
+  return true;
 }
 
 void PrefService::ReloadPersistentPrefs() {
   DCHECK(CalledOnValidThread());
 
   JSONFileValueSerializer serializer(pref_filename_);
-  Value* root;
-  if (serializer.Deserialize(&root, NULL)) {
-    // Preferences should always have a dictionary root.
-    if (!root->IsType(Value::TYPE_DICTIONARY)) {
-      delete root;
-      return;
-    }
+  scoped_ptr<Value> root(serializer.Deserialize(NULL));
+  if (!root.get())
+    return;
 
-    persistent_.reset(static_cast<DictionaryValue*>(root));
-    for (PreferenceSet::iterator it = prefs_.begin();
-         it != prefs_.end(); ++it) {
-      (*it)->root_pref_ = persistent_.get();
-    }
+  // Preferences should always have a dictionary root.
+  if (!root->IsType(Value::TYPE_DICTIONARY))
+    return;
+
+  persistent_.reset(static_cast<DictionaryValue*>(root.release()));
+  for (PreferenceSet::iterator it = prefs_.begin();
+       it != prefs_.end(); ++it) {
+    (*it)->root_pref_ = persistent_.get();
   }
 }
 
diff --git a/chrome/common/pref_service_uitest.cc b/chrome/common/pref_service_uitest.cc
index b9f0774..0ecd114 100644
--- a/chrome/common/pref_service_uitest.cc
+++ b/chrome/common/pref_service_uitest.cc
@@ -82,13 +82,12 @@ TEST_F(PreferenceServiceTest, PreservedWindowPlacementIsLoaded) {
   ASSERT_TRUE(file_util::PathExists(tmp_pref_file_));
 
   JSONFileValueSerializer deserializer(tmp_pref_file_);
-  Value* root = NULL;
-  ASSERT_TRUE(deserializer.Deserialize(&root, NULL));
+  scoped_ptr<Value> root(deserializer.Deserialize(NULL));
 
-  ASSERT_TRUE(root);
+  ASSERT_TRUE(root.get());
   ASSERT_TRUE(root->IsType(Value::TYPE_DICTIONARY));
 
-  DictionaryValue* root_dict = static_cast<DictionaryValue*>(root);
+  DictionaryValue* root_dict = static_cast<DictionaryValue*>(root.get());
 
   // Retrieve the screen rect for the launched window
   scoped_ptr<BrowserProxy> browser(automation()->GetBrowserWindow(0));
@@ -130,6 +129,5 @@ TEST_F(PreferenceServiceTest, PreservedWindowPlacementIsLoaded) {
   ASSERT_TRUE(root_dict->GetBoolean(kBrowserWindowPlacement + L".maximized",
       &is_maximized));
   ASSERT_EQ(is_maximized, is_window_maximized);
-  delete root;
 }
 
diff --git a/chrome/common/pref_service_unittest.cc b/chrome/common/pref_service_unittest.cc
index 2baa908..e35e44a 100644
--- a/chrome/common/pref_service_unittest.cc
+++ b/chrome/common/pref_service_unittest.cc
@@ -155,14 +155,16 @@ TEST_F(PrefServiceTest, Overlay) {
   Value* transient_value;
   {
     JSONStringValueSerializer serializer(transient);
-    ASSERT_TRUE(serializer.Deserialize(&transient_value, NULL));
+    transient_value = serializer.Deserialize(NULL);
+    ASSERT_TRUE(transient_value);
   }
   prefs.transient()->Set(transient_string, transient_value);
 
   Value* both_transient_value;
   {
     JSONStringValueSerializer serializer(transient);
-    ASSERT_TRUE(serializer.Deserialize(&both_transient_value, NULL));
+    both_transient_value = serializer.Deserialize(NULL);
+    ASSERT_TRUE(both_transient_value);
   }
   prefs.transient()->Set(L"both", both_transient_value);
 
diff --git a/chrome/installer/util/master_preferences.cc b/chrome/installer/util/master_preferences.cc
index 34d10a9..21c74dd 100644
--- a/chrome/installer/util/master_preferences.cc
+++ b/chrome/installer/util/master_preferences.cc
@@ -12,14 +12,13 @@ namespace {
 
 DictionaryValue* ReadJSONPrefs(const std::string& data) {
   JSONStringValueSerializer json(data);
-  Value* root;
-  if (!json.Deserialize(&root, NULL))
+  scoped_ptr<Value> root(json.Deserialize(NULL));
+  if (!root.get())
     return NULL;
-  if (!root->IsType(Value::TYPE_DICTIONARY)) {
-    delete root;
+  if (!root->IsType(Value::TYPE_DICTIONARY))
     return NULL;
-  }
-  return static_cast<DictionaryValue*>(root);
+
+  return static_cast<DictionaryValue*>(root.release());
 }
 
 bool GetBooleanPref(const DictionaryValue* prefs, const std::wstring& name) {
diff --git a/chrome/test/automation/tab_proxy.cc b/chrome/test/automation/tab_proxy.cc
index f17a35de..07a3488 100644
--- a/chrome/test/automation/tab_proxy.cc
+++ b/chrome/test/automation/tab_proxy.cc
@@ -555,10 +555,10 @@ bool TabProxy::ExecuteAndExtractValue(const std::wstring& frame_xpath,
   json.append("]");
 
   JSONStringValueSerializer deserializer(json);
-  succeeded = deserializer.Deserialize(value, NULL);
+  *value = deserializer.Deserialize(NULL);
 
   delete response;
-  return succeeded;
+  return *value != NULL;
 }
 
 bool TabProxy::GetConstrainedWindowCount(int* count) const {
diff --git a/chrome/test/ui/ui_test.cc b/chrome/test/ui/ui_test.cc
index 4d58e6a..e1bea1b 100644
--- a/chrome/test/ui/ui_test.cc
+++ b/chrome/test/ui/ui_test.cc
@@ -497,13 +497,11 @@ static DictionaryValue* LoadDictionaryValueFromPath(const std::wstring& path) {
     return NULL;
 
   JSONFileValueSerializer serializer(path);
-  Value* root_value = NULL;
-  if (serializer.Deserialize(&root_value, NULL) &&
-      root_value->GetType() != Value::TYPE_DICTIONARY) {
-    delete root_value;
+  scoped_ptr<Value> root_value(serializer.Deserialize(NULL));
+  if (!root_value.get() || root_value->GetType() != Value::TYPE_DICTIONARY)
     return NULL;
-  }
-  return static_cast<DictionaryValue*>(root_value);
+
+  return static_cast<DictionaryValue*>(root_value.release());
 }
 
 DictionaryValue* UITest::GetLocalState() {