Removing x-x509-user-cert mime handler.

chrome/browser/download/chrome_download_manager_delegate.cc

Index: chrome/browser/download/chrome_download_manager_delegate.cc
diff --git a/chrome/browser/download/chrome_download_manager_delegate.cc b/chrome/browser/download/chrome_download_manager_delegate.cc
index 3d609fb2e733224ca63ce2239f094415f6a16373..4e4a18cb7d7c7d9c59d205280b01663341f0336a 100644
--- a/chrome/browser/download/chrome_download_manager_delegate.cc
+++ b/chrome/browser/download/chrome_download_manager_delegate.cc
@@ -465,6 +465,13 @@ void ChromeDownloadManagerDelegate::OpenDownload(DownloadItem* download) {
       NEW_FOREGROUND_TAB,
       ui::PAGE_TRANSITION_LINK,
       false);
+
+  if (download->GetOriginalMimeType() == "application/x-x509-user-cert") {
+    params = content::OpenURLParams(GURL("chrome://settings/certificates"),
+                                    content::Referrer(), NEW_FOREGROUND_TAB,
+                                    ui::PAGE_TRANSITION_LINK, false);
+  }
+
   browser->OpenURL(params);
   RecordDownloadOpenMethod(DOWNLOAD_OPEN_METHOD_DEFAULT_BROWSER);
 #else
@@ -720,6 +727,11 @@ void ChromeDownloadManagerDelegate::OnDownloadTargetDetermined(
         target_info->is_filetype_handled_safely)
       DownloadItemModel(item).SetShouldPreferOpeningInBrowser(true);
 
+#if defined(OS_LINUX) || defined(OS_CHROMEOS)
+    if (item->GetOriginalMimeType() == "application/x-x509-user-cert")
+      DownloadItemModel(item).SetShouldPreferOpeningInBrowser(true);
+#endif
+
     if (target_info->is_dangerous_file)
       DownloadItemModel(item).SetIsDangerousFileBasedOnType(true);
   }