Display "Restart to update" dialog to Chrome OS users.

chrome/browser/ui/ash/system_tray_delegate_chromeos.h

Index: chrome/browser/ui/ash/system_tray_delegate_chromeos.h
diff --git a/chrome/browser/ui/ash/system_tray_delegate_chromeos.h b/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
index db10ab44d5cb6524d8f43f921a7b86e28947cd50..bb839411a35b3f4c5f6573d624daed982d621245 100644
--- a/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
+++ b/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
@@ -70,6 +70,10 @@ class SystemTrayDelegateChromeOS
 
   ~SystemTrayDelegateChromeOS() override;
 
+  // Access a global pointer to the single instance of the
+  // SystemTrayDelegateChromeOS class.
+  static SystemTrayDelegateChromeOS* instance();
+
   void InitializeOnAdapterReady(
       scoped_refptr<device::BluetoothAdapter> adapter);
 
@@ -123,6 +127,11 @@ class SystemTrayDelegateChromeOS
 
   void UserChangedChildStatus(user_manager::User* user) override;
 
+  // This notifies the system that a flash update is now available, and so the
+  // user should reboot.
+  void SetFlashUpdateAvailable();
+  bool GetFlashUpdateAvailable();
+
  private:
   ash::SystemTrayNotifier* GetSystemTrayNotifier();
 
@@ -235,6 +244,7 @@ class SystemTrayDelegateChromeOS
   std::string enterprise_realm_;
   bool should_run_bluetooth_discovery_ = false;
   bool session_started_ = false;
+  bool flash_update_available_ = false;
 
   scoped_refptr<device::BluetoothAdapter> bluetooth_adapter_;
   std::unique_ptr<device::BluetoothDiscoverySession>