Use mojo SystemTray interfaces for both mash and classic ash

chrome/browser/ui/ash/system_tray_delegate_chromeos.h

Index: chrome/browser/ui/ash/system_tray_delegate_chromeos.h
diff --git a/chrome/browser/ui/ash/system_tray_delegate_chromeos.h b/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
index def75b50cec9e80b0584b0d608e1f397a4feed43..02844f468f355e3f19343213fc66b681130ad658 100644
--- a/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
+++ b/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
@@ -70,7 +70,6 @@ class SystemTrayDelegateChromeOS
       public user_manager::UserManager::UserSessionStateObserver,
       public SupervisedUserServiceObserver,
       public ShutdownPolicyHandler::Delegate,
-      public system::SystemClockObserver,
       public input_method::InputMethodManager::ImeMenuObserver {
  public:
   SystemTrayDelegateChromeOS();
@@ -92,10 +91,8 @@ class SystemTrayDelegateChromeOS
   bool IsUserSupervised() const override;
   bool IsUserChild() const override;
   void GetSystemUpdateInfo(ash::UpdateInfo* info) const override;
-  base::HourClockType GetHourClockType() const override;
   void ShowSettings() override;
   bool ShouldShowSettings() override;
-  void ShowDateSettings() override;
   void ShowSetTimeDialog() override;
   void ShowNetworkSettingsForGuid(const std::string& guid) override;
   void ShowDisplaySettings() override;
@@ -164,9 +161,6 @@ class SystemTrayDelegateChromeOS
   // browser tests need to call ShouldUse24HourClock().
   bool GetShouldUse24HourClockForTesting() const;
 
-  // chromeos::system::SystemClockObserver implementation.
-  void OnSystemClockChanged(system::SystemClock*) override;
-
  private:
   ash::SystemTray* GetPrimarySystemTray();