Fix a crash caused by unknown saved language.

chrome/browser/translate/translate_infobar_delegate.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_infobar_delegate.h"
 
 #include <algorithm>
 
 #include "base/metrics/histogram.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 71 matching lines @@
   DCHECK_LT(language_index, GetLanguageCount());
   original_language_index_ = language_index;
   if (infobar_view_)
     infobar_view_->OriginalLanguageChanged();
   if (type_ == AFTER_TRANSLATE)
     Translate();
 }
 
 void TranslateInfoBarDelegate::SetTargetLanguage(size_t language_index) {
   DCHECK_LT(language_index, GetLanguageCount());
+  DCHECK_GE(language_index, 0U);
   target_language_index_ = language_index;
   if (infobar_view_)
     infobar_view_->TargetLanguageChanged();
   if (type_ == AFTER_TRANSLATE)
     Translate();
 }
 
 void TranslateInfoBarDelegate::Translate() {
   const std::string& original_language_code = GetOriginalLanguageCode();
   if (!tab_contents()->browser_context()->IsOffTheRecord()) {
@@ skipping 239 matching lines @@
   for (std::vector<LanguageNamePair>::const_iterator iter = languages_.begin();
        iter != languages_.end(); ++iter) {
     std::string language_code = iter->first;
     if (language_code == original_language) {
       original_language_index_ = iter - languages_.begin();
       initial_original_language_index_ = original_language_index_;
     }
     if (language_code == target_language)
       target_language_index_ = iter - languages_.begin();
   }
+  DCHECK_NE(kNoIndex, target_language_index_);
 }
 
 bool TranslateInfoBarDelegate::ShouldExpire(
     const content::LoadCommittedDetails& details) const {
   // Note: we allow closing this infobar even if the main frame navigation
   // was programmatic and not initiated by the user - crbug.com/70261 .
   if (!details.is_navigation_to_different_page() && !details.is_main_frame)
     return false;
 
   return InfoBarDelegate::ShouldExpireInternal(details);
@@ skipping 19 matching lines @@
 
 TranslateInfoBarDelegate*
     TranslateInfoBarDelegate::AsTranslateInfoBarDelegate() {
   return this;
 }
 
 std::string TranslateInfoBarDelegate::GetPageHost() {
   NavigationEntry* entry = tab_contents_->controller().GetActiveEntry();
   return entry ? entry->url().HostNoBrackets() : std::string();
 }