[Linux] Use PR_SET_NO_NEW_PRIVS by default in base/process/launch.h.

chrome/browser/sessions/session_restore_browsertest.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 <vector>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/process/launch.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 905 matching lines @@
 #endif
 
   ui_test_utils::NavigateToURL(browser(), url1_);
 
   // Launch an app.
   CommandLine app_launch_arguments = GetCommandLineForRelaunch();
   app_launch_arguments.AppendSwitchASCII(switches::kApp, url2_.spec());
 
   ui_test_utils::BrowserAddedObserver window_observer;
 
-  base::LaunchProcess(app_launch_arguments, base::LaunchOptions(), NULL);
+  base::LaunchOptions options;
+#if defined(OS_LINUX)
+  // To prevent accidental privilege sharing to an untrusted child, processes
+  // are started with PR_SET_NO_NEW_PRIVS. Do not set that here, since this
+  // new child will be a test browser process.
+  options.allow_new_privs = true;
+#endif
+  base::LaunchProcess(app_launch_arguments, options, NULL);
 
   Browser* app_window = window_observer.WaitForSingleNewBrowser();
   ASSERT_EQ(2u, active_browser_list_->size());
 
   // Close the first window. The only window left is the App window.
   CloseBrowserSynchronously(browser());
 
   // Restore the session, which should bring back the first window with url1_.
   Browser* new_browser = QuitBrowserAndRestore(app_window, 1);
 
@@ skipping 245 matching lines @@
   content::NavigationController* controller =
       &browser()->tab_strip_model()->GetActiveWebContents()->GetController();
   EXPECT_TRUE(
       controller->GetDefaultSessionStorageNamespace()->should_persist());
 
   // Quit and restore. Check that no extra tabs were created.
   Browser* new_browser = QuitBrowserAndRestore(browser(), 1);
   ASSERT_EQ(1u, active_browser_list_->size());
   EXPECT_EQ(1, new_browser->tab_strip_model()->count());
 }