POSIX: treat multiple extensions like .tar.gz as a single extension.

chrome/browser/download/download_manager.cc

 // Copyright (c) 2010 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/download/download_manager.h"
 
 #include "app/l10n_util.h"
 #include "app/resource_bundle.h"
 #include "base/callback.h"
 #include "base/file_util.h"
@@ skipping 1132 matching lines @@
   if (extension.empty()) {
     net::GetPreferredExtensionForMimeType(mime_type, &extension);
   } else {
     // Append extension generated from the mime type if:
     // 1. New extension is not ".txt"
     // 2. New extension is not the same as the already existing extension.
     // 3. New extension is not executable. This action mitigates the case when
     //    an executable is hidden in a benign file extension;
     //    E.g. my-cat.jpg becomes my-cat.jpg.js if content type is
     //         application/x-javascript.
-    // 4. New extension is not ".tar" for .gz files. For misconfigured web
+    // 4. New extension is not ".tar" for .tar.gz files. For misconfigured web
     //    servers, i.e. bug 5772.
     // 5. The original extension is not ".tgz" & the new extension is not "gz".
     FilePath::StringType append_extension;
     if (net::GetPreferredExtensionForMimeType(mime_type, &append_extension)) {
       if (append_extension != FILE_PATH_LITERAL("txt") &&
           append_extension != extension &&
           !IsExecutableExtension(append_extension) &&
           !(append_extension == FILE_PATH_LITERAL("gz") &&
             extension == FILE_PATH_LITERAL("tgz")) &&
           (append_extension != FILE_PATH_LITERAL("tar") ||
-           extension != FILE_PATH_LITERAL("gz"))) {
+           extension != FILE_PATH_LITERAL("tar.gz"))) {
         extension += FILE_PATH_LITERAL(".");
         extension += append_extension;
       }
     }
   }
 
   generated_extension->swap(extension);
 }
 
 void DownloadManager::GenerateFileNameFromInfo(DownloadCreateInfo* info,
@@ skipping 457 matching lines @@
   observing_download_manager_->NotifyModelChanged();
 }
 
 void DownloadManager::OtherDownloadManagerObserver::SetDownloads(
     std::vector<DownloadItem*>& downloads) {
 }
 
 void DownloadManager::OtherDownloadManagerObserver::ManagerGoingDown() {
   observed_download_manager_ = NULL;
 }