Add option to open PDFs in system viewer to OS X and Linux.

chrome/browser/download/chrome_download_manager_delegate.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/download/chrome_download_manager_delegate.h"
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 701 matching lines @@
       DownloadItemModel(item).SetIsDangerousFileBasedOnType(true);
   }
   callback.Run(target_info->target_path,
                target_info->target_disposition,
                target_info->danger_type,
                target_info->intermediate_path);
 }
 
 bool ChromeDownloadManagerDelegate::IsOpenInBrowserPreferreredForFile(
     const base::FilePath& path) {
-  // On Windows, PDFs should open in Acrobat Reader if the user chooses.
-#if defined(OS_WIN)
-  if (path.MatchesExtension(FILE_PATH_LITERAL(".pdf")) &&
-      DownloadTargetDeterminer::IsAdobeReaderUpToDate()) {
-    return !download_prefs_->ShouldOpenPdfInAdobeReader();
+#if defined(OS_WIN) || defined(OS_LINUX) || \
+    (defined(OS_MACOSX) && !defined(OS_IOS))
+  if (path.MatchesExtension(FILE_PATH_LITERAL(".pdf"))) {
+    return !download_prefs_->ShouldOpenPdfInSystemReader();
   }
 #endif
 
   // On Android, always prefer opening with an external app. On ChromeOS, there
   // are no external apps so just allow all opens to be handled by the "System."
 #if !defined(OS_ANDROID) && !defined(OS_CHROMEOS) && defined(ENABLE_PLUGINS)
   // TODO(asanka): Consider other file types and MIME types.
   // http://crbug.com/323561
   if (path.MatchesExtension(FILE_PATH_LITERAL(".pdf")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".htm")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".html")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".shtm")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".shtml")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".svg")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xht")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xhtm")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xhtml")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xsl")) ||
       path.MatchesExtension(FILE_PATH_LITERAL(".xslt"))) {
     return true;
   }
 #endif
   return false;
 }