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

chrome/browser/sessions/session_restore_browsertest.cc

Index: chrome/browser/sessions/session_restore_browsertest.cc
diff --git a/chrome/browser/sessions/session_restore_browsertest.cc b/chrome/browser/sessions/session_restore_browsertest.cc
index 25c306d05b56fa934e3a47a0ef0d5325b16fc749..9ff6d504fa1c04df8eb5e0cb093e8ddd0749c757 100644
--- a/chrome/browser/sessions/session_restore_browsertest.cc
+++ b/chrome/browser/sessions/session_restore_browsertest.cc
@@ -923,7 +923,14 @@ IN_PROC_BROWSER_TEST_F(SessionRestoreTest,
 
   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.

[Nico, 2014/04/02 01:44:17]

Since this is in a few places, would it make sense to have a
base::LaunchProcessForTesting() (maybe in a testing namespace) which does this?

[Robert Sesek, 2014/04/02 15:39:22]

I don't know. It seems weird to expose new base/ API functions for basically
setting a single flag. If you think that's fine, I'll do it, but I'm not quite
sure it's warranted.

[Nico, 2014/04/02 15:43:58]

I think it makes sense: Currently, the same 8 lines are repeated in 4+ places,
and if the new function has a good name the callers would express intent more
clearly. (But I lgtm'd without that too, so I don't insist on this if you thing
it's a bad idea.)

[Robert Sesek, 2014/04/02 19:57:04]

Fair enough. I didn't like creating a new LaunchProcess variant, but I added a
helper LaunchOptionsForTest() to return a base::LaunchOptions configured for a
test environment.

+  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());