Fix a crash in the translate info bar.

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 17 matching lines @@
     Type type,
     TabContents* tab_contents,
     const std::string& original_language,
     const std::string& target_language) {
   DCHECK_NE(TRANSLATION_ERROR, type);
   // The original language can only be "unknown" for the "translating"
   // infobar, which is the case when the user started a translation from the
   // context menu.
   DCHECK(type == TRANSLATING ||
       original_language != chrome::kUnknownLanguageCode);
-  if ((original_language != chrome::kUnknownLanguageCode &&
-          !TranslateManager::IsSupportedLanguage(original_language)) ||
-      !TranslateManager::IsSupportedLanguage(target_language))
-    return NULL;
+  // This must be validated by our callers.

[Peter Kasting, 2011/08/08 22:09:49]

Nit: How about this for comments and checks:

In header:

// Factory method to create a non-error translate infobar.  |original_language|
// and |target_language| must be ASCII language codes (e.g. "en", "fr", etc.)
// for languages the TranslateManager supports translating.  The lone exception
// is when the user initiates translation from the context menu, in which case
// it's legal to call this with |type| == TRANSLATING and
// |originalLanguage| == kUnknownLanguageCode.
... (declaration) ...;

In .cc file:

... (declaration) ... {
  DCHECK_NE(TRANSLATION_ERROR, type);
  DCHECK(TranslateManager::IsSupportedLanguage(original_language) ||
      ((type == TRANSLATING) &&
       (original_language == chrome::kUnknownLanguageCode)));
  DCHECK(TranslateManager::IsSupportedLanguage(target_language));
  ... (function body) ...

[MAD, 2011/08/09 14:19:41]

Done.

+  CHECK((original_language == chrome::kUnknownLanguageCode ||
+         TranslateManager::IsSupportedLanguage(original_language)) &&
+        TranslateManager::IsSupportedLanguage(target_language));
   TranslateInfoBarDelegate* delegate =
       new TranslateInfoBarDelegate(type, TranslateErrors::NONE, tab_contents,
                                    original_language, target_language);
   DCHECK_NE(kNoIndex, delegate->target_language_index());
   return delegate;
 }
 
 TranslateInfoBarDelegate* TranslateInfoBarDelegate::CreateErrorDelegate(
     TranslateErrors::Type error,
     TabContents* tab_contents,
@@ skipping 329 matching lines @@
 
 TranslateInfoBarDelegate*
     TranslateInfoBarDelegate::AsTranslateInfoBarDelegate() {
   return this;
 }
 
 std::string TranslateInfoBarDelegate::GetPageHost() {
   NavigationEntry* entry = tab_contents_->controller().GetActiveEntry();
   return entry ? entry->url().HostNoBrackets() : std::string();
 }