Bug 40036: added a test to check that permissions are not saved on storage

In our Firefox patch set we have a test that assures that preferences
are kept in memory, instead of saving them to the disk or other
storage.
However, usually we check this kind of functionality here, not on
the Firefox/tor-browser code.

Other tests in that tor-browser commit should already be covered.

TBBTestSuite/TestSuite/BrowserBundleTests.pm

@@ -465,6 +465,12 @@ our @tests = (
         use_net         => 1,
         descr           => 'Check that the security level UI is working properly',
     },
+    {
+        name            => 'volatile_preferences',
+        type            => 'marionette',
+        use_net         => 0,
+        descr           => 'Check that the site preferences are not saved to disk',
+    }
 );
 
 sub set_test_prefs {

marionette/tor_browser_tests/test_volatile_preferences.py

+import os.path
+
+from marionette_harness import MarionetteTestCase
+import testsuite
+
+class Test(MarionetteTestCase):
+
+    def test_volatile_preferences(self):
+        with self.marionette.using_context('chrome'):
+            profile_path = self.marionette.execute_script('''
+return Services.dirsvc.get("ProfD", Components.interfaces.nsIFile).path;
+''')
+            # This file does not exist by default in Tor Browser
+            perm_file = profile_path + '/permissions.sqlite'
+            self.assertFalse(os.path.exists(perm_file))
+            script = '''
+const SITE = "https://www.torproject.org";
+const KEY = "storageAccessAPI";
+const principal = Services.scriptSecurityManager.createContentPrincipalFromOrigin(SITE);
+SitePermissions.setForPrincipal(principal, KEY, SitePermissions.ALLOW);
+return SitePermissions.getForPrincipal(principal, KEY).state == SitePermissions.ALLOW;
+'''
+            script_succeeded = self.marionette.execute_script(script)
+            self.assertTrue(script_succeeded)
+            self.assertFalse(os.path.exists(perm_file))