Adds TraySessionLengthLimitTest to ash_unittests.

ash/test/test_system_tray_delegate.cc

Index: ash/test/test_system_tray_delegate.cc
diff --git a/ash/test/test_system_tray_delegate.cc b/ash/test/test_system_tray_delegate.cc
index 0f47aeaa7c1f54fa4f88c2603ac68cb470d213de..473802d5f8f1bab1d3cf8c38c8e5fbc96c61316d 100644
--- a/ash/test/test_system_tray_delegate.cc
+++ b/ash/test/test_system_tray_delegate.cc
@@ -22,7 +22,8 @@ user::LoginStatus g_initial_status = user::LOGGED_IN_USER;
 
 TestSystemTrayDelegate::TestSystemTrayDelegate()
     : should_show_display_notification_(false),
-      login_status_(g_initial_status) {
+      login_status_(g_initial_status),
+      session_length_limit_set_(false) {
 }
 
 TestSystemTrayDelegate::~TestSystemTrayDelegate() {
@@ -39,6 +40,16 @@ void TestSystemTrayDelegate::SetLoginStatus(user::LoginStatus login_status) {
   Shell::GetInstance()->UpdateAfterLoginStatusChange(login_status);
 }
 
+void TestSystemTrayDelegate::SetSessionLengthLimitForTest(
+    const base::TimeDelta& new_limit) {
+  session_length_limit_ = new_limit;
+  session_length_limit_set_ = true;
+}
+
+void TestSystemTrayDelegate::ClearSessionLengthLimit() {
+  session_length_limit_set_ = false;
+}
+
 user::LoginStatus TestSystemTrayDelegate::GetUserLoginStatus() const {
   // Initial login status has been changed for testing.
   if (g_initial_status != user::LOGGED_IN_USER &&
@@ -62,6 +73,22 @@ bool TestSystemTrayDelegate::ShouldShowDisplayNotification() {
   return should_show_display_notification_;
 }
 
+bool TestSystemTrayDelegate::GetSessionStartTime(
+    base::TimeTicks* session_start_time) {
+  // Just returns TimeTicks::Now(), so the remaining time is always the
+  // specified limit. This is useful for testing.
+  if (session_length_limit_set_)
+    *session_start_time = base::TimeTicks::Now();
+  return session_length_limit_set_;
+}
+
+bool TestSystemTrayDelegate::GetSessionLengthLimit(
+    base::TimeDelta* session_length_limit) {
+  if (session_length_limit_set_)
+    *session_length_limit = session_length_limit_;
+  return session_length_limit_set_;
+}
+
 void TestSystemTrayDelegate::ShutDown() {
   base::MessageLoop::current()->Quit();
 }