Adds TraySessionLengthLimitTest to ash_unittests.

ash/test/test_system_tray_delegate.h

 // Copyright 2013 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.
 
 #ifndef ASH_TEST_TEST_SYSTEM_TRAY_DELEGATE_H_
 #define ASH_TEST_TEST_SYSTEM_TRAY_DELEGATE_H_
 
 #include "ash/system/tray/default_system_tray_delegate.h"
+#include "base/time/time.h"
 
 namespace ash {
 namespace test {
 
 class TestSystemTrayDelegate : public DefaultSystemTrayDelegate {
  public:
   TestSystemTrayDelegate();
   virtual ~TestSystemTrayDelegate();
 
   // Changes the login status when initially the delegate is created. This will
   // be called before AshTestBase::SetUp() to test the case when chrome is
   // restarted right after the login (such like a flag is set).
   // This value will be reset in AshTestHelper::TearDown,  most test fixtures
   // don't need to care its lifecycle.
   static void SetInitialLoginStatus(user::LoginStatus login_status);
 
   // Changes the current login status in the test. This also invokes
   // UpdateAfterLoginStatusChange(). Usually this is called in the test code to
   // set up a login status. This will fit to most of the test cases, but this
   // cannot be set during the initialization. To test the initialization,
   // consider using SetInitialLoginStatus() instead.
   void SetLoginStatus(user::LoginStatus login_status);
 
   void set_should_show_display_notification(bool should_show) {
     should_show_display_notification_ = should_show;
   }
 
+  // Updates the session length limit so that the limit will come from now in
+  // |new_limit|.
+  void SetSessionLengthLimitForTest(const base::TimeDelta& new_limit);
+
+  // Clears the session length limit.
+  void ClearSessionLengthLimit();
+
   // Overridden from SystemTrayDelegate:
   virtual user::LoginStatus GetUserLoginStatus() const OVERRIDE;
   virtual bool ShouldShowDisplayNotification() OVERRIDE;
+  virtual bool GetSessionStartTime(
+      base::TimeTicks* session_start_time) OVERRIDE;
+  virtual bool GetSessionLengthLimit(
+      base::TimeDelta* session_length_limit) OVERRIDE;
   virtual void ShutDown() OVERRIDE;
   virtual void SignOut() OVERRIDE;
 
  private:
   bool should_show_display_notification_;
   user::LoginStatus login_status_;
+  base::TimeDelta session_length_limit_;
+  bool session_length_limit_set_;
 
   DISALLOW_COPY_AND_ASSIGN(TestSystemTrayDelegate);
 };
 
 }  // namespace test
 }  // namespace ash
 
 #endif  // ASH_TEST_TEST_SYSTEM_TRAY_DELEGATE_H_