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

ash/common/system/tray/system_tray_delegate.h

Index: ash/common/system/tray/system_tray_delegate.h
diff --git a/ash/common/system/tray/system_tray_delegate.h b/ash/common/system/tray/system_tray_delegate.h
index 5c4de80ebd3808bb956f64740a727d5298067dab..93fef87ad3ba336243ac422517ef33f1e4542d60 100644
--- a/ash/common/system/tray/system_tray_delegate.h
+++ b/ash/common/system/tray/system_tray_delegate.h
@@ -29,6 +29,8 @@ namespace ash {
 
 class CustodianInfoTrayObserver;
 class ShutdownPolicyObserver;
+class SystemTray;
+class SystemTrayItem;
 
 struct ASH_EXPORT NetworkIconInfo {
   NetworkIconInfo();
@@ -183,6 +185,10 @@ class ASH_EXPORT SystemTrayDelegate {
   // show the settings for the corresponding network.
   virtual void ShowNetworkSettingsForGuid(const std::string& guid);
 
+  // Creates the system tray item for display settings.

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

nit: Move far down (not amid Show* functions). Despite a minor relation to
ShowDisplaySettings(), it's rather distinct and a short-term measure that should
be removed later (right?). Maybe add a comment about the long-term plan here?

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

Done.

+  virtual std::unique_ptr<SystemTrayItem> CreateDisplayTrayItem(
+      SystemTray* tray);
+
   // Shows settings related to multiple displays.
   virtual void ShowDisplaySettings();