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

ash/common/system/update/tray_update.h

Index: ash/common/system/update/tray_update.h
diff --git a/ash/common/system/update/tray_update.h b/ash/common/system/update/tray_update.h
index 5cf23f7002701f4e9837b28117fe9aaf4a2c23b5..3850804bc888a2ba3efca6e12f41ecdae7475540 100644
--- a/ash/common/system/update/tray_update.h
+++ b/ash/common/system/update/tray_update.h
@@ -7,7 +7,6 @@
 
 #include "ash/ash_export.h"
 #include "ash/common/system/tray/tray_image_item.h"
-#include "ash/common/system/update/update_observer.h"
 #include "base/macros.h"
 
 namespace views {
@@ -16,19 +15,37 @@ class View;
 
 namespace ash {
 
-// The system update tray item. Exported for test.
-class ASH_EXPORT TrayUpdate : public TrayImageItem, public UpdateObserver {
+namespace mojom {
+enum class UpdateSeverity;
+}
+
+// The system update tray item. The tray icon stays visible once an update
+// notification is received. The icon only disappears after a reboot to apply
+// the update. Exported for test.
+class ASH_EXPORT TrayUpdate : public TrayImageItem {
  public:
   explicit TrayUpdate(SystemTray* system_tray);
   ~TrayUpdate() override;
 
+  // Shows an icon in the system tray indicating that a software update is
+  // available. Once shown the icon persists until reboot. |severity| and
+  // |factory_reset_required| are used to set the icon, color, and tooltip.
+  void ShowUpdateIcon(mojom::UpdateSeverity severity,
+                      bool factory_reset_required);
+
  private:
+  class UpdateView;
+
   // Overridden from TrayImageItem.
   bool GetInitialVisibility() override;
   views::View* CreateDefaultView(LoginStatus status) override;
 
-  // Overridden from UpdateObserver.
-  void OnUpdateRecommended(const UpdateInfo& info) override;
+  // If an external monitor is connected then the system tray may be created
+  // after the update data is sent from chrome, so share the update info between
+  // all instances.
+  static bool update_required_;
+  static mojom::UpdateSeverity severity_;
+  static bool factory_reset_required_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayUpdate);
 };