Re-enable PolicyTest.SessionLengthLimit.

chrome/browser/policy/policy_browsertest.cc

Index: chrome/browser/policy/policy_browsertest.cc
diff --git a/chrome/browser/policy/policy_browsertest.cc b/chrome/browser/policy/policy_browsertest.cc
index cb230b6dbd383a6273726c2f41ae7f4da8cd6fa3..493502bf0c78bbdf57f658d8429bbcc83b625697 100644
--- a/chrome/browser/policy/policy_browsertest.cc
+++ b/chrome/browser/policy/policy_browsertest.cc
@@ -2873,8 +2873,7 @@ IN_PROC_BROWSER_TEST_F(PolicyTest, DisableAudioOutput) {
   audio_handler->RemoveAudioObserver(test_observer.get());
 }
 
-// Disabled, see http://crbug.com/315308.
-IN_PROC_BROWSER_TEST_F(PolicyTest, DISABLED_PRE_SessionLengthLimit) {
+IN_PROC_BROWSER_TEST_F(PolicyTest, PRE_SessionLengthLimit) {
   // Indicate that the session started 2 hours ago and no user activity has
   // occurred yet.
   g_browser_process->local_state()->SetInt64(
@@ -2883,8 +2882,7 @@ IN_PROC_BROWSER_TEST_F(PolicyTest, DISABLED_PRE_SessionLengthLimit) {
           .ToInternalValue());
 }
 
-// Disabled, see http://crbug.com/315308.
-IN_PROC_BROWSER_TEST_F(PolicyTest, DISABLED_SessionLengthLimit) {
+IN_PROC_BROWSER_TEST_F(PolicyTest, SessionLengthLimit) {
   content::MockNotificationObserver observer;
   content::NotificationRegistrar registrar;
   registrar.Add(&observer,