detect preferences errors

chrome/browser/extensions/external_pref_extension_provider.cc

 // Copyright (c) 2009 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.
 
 #include "chrome/browser/extensions/external_pref_extension_provider.h"
 
 #include "app/app_paths.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
@@ skipping 80 matching lines @@
     return NULL;
 
   if (location)
     *location = Extension::EXTERNAL_PREF;
   return Version::GetVersionFromString(external_version);
 }
 
 void ExternalPrefExtensionProvider::SetPreferences(
     ValueSerializer* serializer) {
   std::string error_msg;
-  Value* extensions = serializer->Deserialize(&error_msg);
+  Value* extensions = serializer->Deserialize(NULL, &error_msg);
   scoped_ptr<DictionaryValue> dictionary(new DictionaryValue());
-  if (!error_msg.empty()) {
+  if (!extensions) {
     LOG(WARNING) << L"Unable to deserialize json data: "
-                 << error_msg.c_str();
+                 << error_msg;
   } else {
-    // This can be null if the json file specified does not exist.
-    if (extensions) {
-      if (!extensions->IsType(Value::TYPE_DICTIONARY)) {
-        NOTREACHED() << L"Invalid json data";
-      } else {
-        dictionary.reset(static_cast<DictionaryValue*>(extensions));
-      }
+    if (!extensions->IsType(Value::TYPE_DICTIONARY)) {
+      NOTREACHED() << L"Invalid json data";
+    } else {
+      dictionary.reset(static_cast<DictionaryValue*>(extensions));
     }
   }
   prefs_.reset(dictionary.release());
 }