chromeos: Convert system tray session length limit to mojo

ash/test/test_system_tray_delegate.h

Index: ash/test/test_system_tray_delegate.h
diff --git a/ash/test/test_system_tray_delegate.h b/ash/test/test_system_tray_delegate.h
index 86e17f4a7517d5c4463fe0a3d6b8ca4682484467..38548c020603ddbb2b020ab35355aad7832840f9 100644
--- a/ash/test/test_system_tray_delegate.h
+++ b/ash/test/test_system_tray_delegate.h
@@ -8,7 +8,6 @@
 #include "ash/system/tray/ime_info.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "base/macros.h"
-#include "base/time/time.h"
 
 namespace ash {
 namespace test {
@@ -18,13 +17,6 @@ class TestSystemTrayDelegate : public SystemTrayDelegate {
   TestSystemTrayDelegate();
   ~TestSystemTrayDelegate() override;
 
-  // 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();
-
   // Sets the IME info.
   void SetCurrentIME(const IMEInfo& info);
 
@@ -32,14 +24,10 @@ class TestSystemTrayDelegate : public SystemTrayDelegate {
   void SetAvailableIMEList(const IMEInfoList& list);
 
   // SystemTrayDelegate:
-  bool GetSessionStartTime(base::TimeTicks* session_start_time) override;
-  bool GetSessionLengthLimit(base::TimeDelta* session_length_limit) override;
   void GetCurrentIME(IMEInfo* info) override;
   void GetAvailableIMEList(IMEInfoList* list) override;
 
  private:
-  base::TimeDelta session_length_limit_;
-  bool session_length_limit_set_ = false;
   IMEInfo current_ime_;
   IMEInfoList ime_list_;