Revert of ash: Use system tray mojo interface to show system update tray icon

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 2c19d6d82d186c80b3591e83f0e4abf0458affbe..6c8a20fcb48e60c24d26a5957bea561c4e1eb112 100644
--- a/ash/common/system/tray/system_tray_delegate.h
+++ b/ash/common/system/tray/system_tray_delegate.h
@@ -50,6 +50,24 @@
 };
 
 using BluetoothDeviceList = std::vector<BluetoothDeviceInfo>;
+
+struct ASH_EXPORT UpdateInfo {
+  enum UpdateSeverity {
+    UPDATE_NONE,
+    UPDATE_LOW,
+    UPDATE_ELEVATED,
+    UPDATE_HIGH,
+    UPDATE_SEVERE,
+    UPDATE_CRITICAL,
+  };
+
+  UpdateInfo();
+  ~UpdateInfo();
+
+  UpdateSeverity severity;
+  bool update_required;
+  bool factory_reset_required;
+};
 
 class NetworkingConfigDelegate;
 
@@ -105,6 +123,9 @@
   // crbug.com/443119
   virtual bool IsUserChild() const;
 
+  // Fills |info| structure (which must not be null) with current update info.
+  virtual void GetSystemUpdateInfo(UpdateInfo* info) const;
+
   // Returns true if settings menu item should appear.
   virtual bool ShouldShowSettings() const;