Do not show translate bar for MHTML files.

chrome/browser/translate/translate_manager.cc

 // Copyright (c) 2012 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_manager.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/memory/singleton.h"
 #include "base/metrics/histogram.h"
@@ skipping 83 matching lines @@
 
 // static
 bool TranslateManager::IsTranslatableURL(const GURL& url) {
   // A URLs is translatable unless it is one of the following:
   // - empty (can happen for popups created with window.open(""))
   // - an internal URL (chrome:// and others)
   // - the devtools (which is considered UI)
   // - Chrome OS file manager extension
   // - an FTP page (as FTP pages tend to have long lists of filenames that may
   //   confuse the CLD)
+  // - an MHTML page (Chrome does not load external resources when displaying
+  //   MHTML pages, see bug 262953)
+
+  // get file extension (empty if URL does not reference a file)

[Miguel Garcia, 2013/07/22 17:42:00]

I'd move this to a method and add a unittest for it (although it is interesting
that no such method exist already, can you double check it's not the case?)

+  std::string file_name, file_extension;
+  size_t path_delim = url.path().rfind('/');
+  if (path_delim != std::string::npos) {
+    file_name = url.path().substr(path_delim+1);
+    size_t file_delim = file_name.rfind('.');
+    if (file_delim != std::string::npos) {
+      file_extension = file_name.substr(file_delim+1);
+    }
+  }
+
   return !url.is_empty() &&
          !url.SchemeIs(chrome::kChromeUIScheme) &&
          !url.SchemeIs(chrome::kChromeDevToolsScheme) &&
 #ifdef FILE_MANAGER_EXTENSION
          !(url.SchemeIs(extensions::kExtensionScheme) &&
            url.DomainIs(kFileBrowserDomain)) &&
 #endif
-         !url.SchemeIs(chrome::kFtpScheme);
+         !url.SchemeIs(chrome::kFtpScheme) &&
+         !(file_extension == "mht" || file_extension == "mhtml");

[Miguel Garcia, 2013/07/22 17:42:00]

create constants perhaps?

 }
 
 // static
 void TranslateManager::GetSupportedLanguages(
     std::vector<std::string>* languages) {
   if (GetInstance()->language_list_.get()) {
     GetInstance()->language_list_->GetSupportedLanguages(languages);
     return;
   }
   NOTREACHED();
@@ skipping 595 matching lines @@
   // so we are more aggressive about showing the shortcut to never translate.
   #if defined(OS_ANDROID)
   config.never_translate_min_count = 1;
   #else
   config.never_translate_min_count = 3;
   #endif  // defined(OS_ANDROID)
 
   config.always_translate_min_count = 3;
   return config;
 }