mash: Create system tray display and rotation lock items via delegate

ash/common/system/tray/system_tray_delegate.cc

Index: ash/common/system/tray/system_tray_delegate.cc
diff --git a/ash/common/system/tray/system_tray_delegate.cc b/ash/common/system/tray/system_tray_delegate.cc
index ee83a0f4d4ae45a914b8dec42fc256a893f48ca7..5234f9761f7a3ff5087e77dec652f9bdafbed838 100644
--- a/ash/common/system/tray/system_tray_delegate.cc
+++ b/ash/common/system/tray/system_tray_delegate.cc
@@ -4,6 +4,8 @@
 
 #include "ash/common/system/tray/system_tray_delegate.h"
 
+#include "ash/common/system/tray/system_tray_item.h"
+
 namespace ash {
 
 NetworkIconInfo::NetworkIconInfo()
@@ -102,6 +104,11 @@ void SystemTrayDelegate::ShowSetTimeDialog() {}
 
 void SystemTrayDelegate::ShowNetworkSettingsForGuid(const std::string& guid) {}
 
+std::unique_ptr<SystemTrayItem> SystemTrayDelegate::CreateDisplayTrayItem(
+    SystemTray* tray) {
+  return nullptr;

[msw, 2016/07/13 18:51:49]

nit: NOTIMPLEMENTED? (seems like others omit, so maybe okay as-is)

[James Cook, 2016/07/13 21:30:46]

I kept it the same since none of the other ones use NOTIMPLEMENTED.

+}
+
 void SystemTrayDelegate::ShowDisplaySettings() {}
 
 void SystemTrayDelegate::ShowPowerSettings() {}