Use mojo SystemTray interfaces for both mash and classic ash

chrome/browser/ui/ash/system_tray_delegate_chromeos.cc

Index: chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
diff --git a/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc b/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
index 46b3cbd86ca8da8d086d9a5853646a6f0e93c291..96681c2f41d117ef9e41f002987062bf4e0a421b 100644
--- a/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
+++ b/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
@@ -236,10 +236,6 @@ void SystemTrayDelegateChromeOS::Initialize() {
   input_method::InputMethodManager::Get()->AddImeMenuObserver(this);
   ui::ime::InputMethodMenuManager::GetInstance()->AddObserver(this);
 
-  g_browser_process->platform_part()->GetSystemClock()->AddObserver(this);
-
-  OnSystemClockChanged(g_browser_process->platform_part()->GetSystemClock());
-
   device::BluetoothAdapterFactory::GetAdapter(
       base::Bind(&SystemTrayDelegateChromeOS::InitializeOnAdapterReady,
                  weak_ptr_factory_.GetWeakPtr()));
@@ -293,7 +289,6 @@ SystemTrayDelegateChromeOS::~SystemTrayDelegateChromeOS() {
   // Unregister a11y status subscription.
   accessibility_subscription_.reset();
 
-  g_browser_process->platform_part()->GetSystemClock()->RemoveObserver(this);
   DBusThreadManager::Get()->GetSessionManagerClient()->RemoveObserver(this);
   input_method::InputMethodManager::Get()->RemoveObserver(this);
   ui::ime::InputMethodMenuManager::GetInstance()->RemoveObserver(this);
@@ -403,10 +398,6 @@ void SystemTrayDelegateChromeOS::GetSystemUpdateInfo(
   GetUpdateInfo(UpgradeDetector::GetInstance(), info);
 }
 
-base::HourClockType SystemTrayDelegateChromeOS::GetHourClockType() const {
-  return clock_type_;
-}
-
 void SystemTrayDelegateChromeOS::ShowSettings() {
   SystemTrayCommon::ShowSettings();
 }
@@ -417,10 +408,6 @@ bool SystemTrayDelegateChromeOS::ShouldShowSettings() {
          !wm_shell->GetSessionStateDelegate()->IsInSecondaryLoginScreen();
 }
 
-void SystemTrayDelegateChromeOS::ShowDateSettings() {
-  SystemTrayCommon::ShowDateSettings();
-}
-
 void SystemTrayDelegateChromeOS::ShowSetTimeDialog() {
   // TODO(mash): Refactor out GetNativeWindow and move to SystemTrayCommon.
   SetTimeDialog::ShowDialog(GetNativeWindow());
@@ -920,13 +907,6 @@ bool SystemTrayDelegateChromeOS::GetShouldUse24HourClockForTesting() const {
       ->ShouldUse24HourClock();
 }
 
-void SystemTrayDelegateChromeOS::OnSystemClockChanged(
-    system::SystemClock* system_clock) {
-  const bool use_24_hour_clock = system_clock->ShouldUse24HourClock();
-  clock_type_ = use_24_hour_clock ? base::k24HourClock : base::k12HourClock;
-  GetSystemTrayNotifier()->NotifyDateFormatChanged();
-}
-
 void SystemTrayDelegateChromeOS::UpdateShowLogoutButtonInTray() {
   GetSystemTrayNotifier()->NotifyShowLoginButtonChanged(
       user_pref_registrar_->prefs()->GetBoolean(