Bug fix: Merging language sets to create 'translate_blocked_languages' may be evaded

chrome/browser/translate/translate_prefs.cc

 // Copyright (c) 2011 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/translate/translate_prefs.h"
 
 #include "base/command_line.h"
 #include "base/prefs/pref_service.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
@@ skipping 306 matching lines @@
   // - original language -> one target language to auto-translate
   // - each time that the user enables the "Always translate..." option, that
   //   target lang overwrites the previous one.
   // - this results in a one-to-one relationship between source lang and target
   //   lang
   // - we replace old list of target langs with the last target lang in list,
   //   assuming the last (i.e. most recent) target lang is what user wants to
   //   keep auto-translated.
   DictionaryPrefUpdate update(user_prefs, kPrefTranslateWhitelists);
   DictionaryValue* dict = update.Get();
-  if (!dict || dict->empty())
-    return;
-  DictionaryValue::Iterator iter(*dict);
-  while (!iter.IsAtEnd()) {
-    const ListValue* list = NULL;
-    if (!iter.value().GetAsList(&list) || !list)
-      break;  // Dictionary has either been migrated or new format.
-    std::string key = iter.key();
-    // Advance the iterator before removing the current element.
-    iter.Advance();
-    std::string target_lang;
-    if (list->empty() || !list->GetString(list->GetSize() - 1, &target_lang) ||
-        target_lang.empty()) {
-      dict->Remove(key, NULL);
-    } else {
-      dict->SetString(key, target_lang);
+  if (dict && !dict->empty()) {
+    DictionaryValue::Iterator iter(*dict);
+    while (!iter.IsAtEnd()) {
+      const ListValue* list = NULL;
+      if (!iter.value().GetAsList(&list) || !list)
+        break;  // Dictionary has either been migrated or new format.
+      std::string key = iter.key();
+      // Advance the iterator before removing the current element.
+      iter.Advance();
+      std::string target_lang;
+      if (list->empty() ||
+          !list->GetString(list->GetSize() - 1, &target_lang) ||
+          target_lang.empty()) {
+        dict->Remove(key, NULL);
+      } else {
+        dict->SetString(key, target_lang);
+      }
     }
   }
 
   // Get the union of the blacklist and the Accept languages, and set this to
   // the new language set 'translate_blocked_languages'. This is used for the
   // settings UI for Translate and configration to determine which langauage
   // should be translated instead of the blacklist. The blacklist is no longer
   // used after launching the settings UI.
   // After that, Set 'translate_languages_not_translate' to Accept languages to
   // enable settings for users.
@@ skipping 130 matching lines @@
 
 bool TranslatePrefs::IsListEmpty(const char* pref_id) const {
   const ListValue* blacklist = prefs_->GetList(pref_id);
   return (blacklist == NULL || blacklist->empty());
 }
 
 bool TranslatePrefs::IsDictionaryEmpty(const char* pref_id) const {
   const DictionaryValue* dict = prefs_->GetDictionary(pref_id);
   return (dict == NULL || dict->empty());
 }