Add ash::VPNDelegate and Chrome OS implementation

ash/system/chromeos/network/vpn_delegate.h

Index: ash/system/chromeos/network/vpn_delegate.h
diff --git a/ash/system/chromeos/network/vpn_delegate.h b/ash/system/chromeos/network/vpn_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..9f28079fc3baecb5321ac6dfd44475e7d693f418
--- /dev/null
+++ b/ash/system/chromeos/network/vpn_delegate.h
@@ -0,0 +1,79 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ASH_SYSTEM_CHROMEOS_NETWORK_VPN_DELEGATE_H
+#define ASH_SYSTEM_CHROMEOS_NETWORK_VPN_DELEGATE_H
+
+#include <string>
+#include <vector>
+
+#include "ash/ash_export.h"
+#include "base/macros.h"
+#include "base/observer_list.h"
+
+namespace ash {
+
+// Describes a third-party VPN provider.
+struct ASH_EXPORT VPNProvider {
+  VPNProvider(const std::string& name, const std::string& id);
+  ~VPNProvider();
+
+  // Human-readable name.
+  const std::string name;
+  // Opaque ID.
+  const std::string id;
+};
+
+// This delegate provides UI code in ash, e.g. |VPNList|, with access to the
+// list of third-party VPN providers enabled in the primary user's profile.
+// The delegate furthermore allows the UI code to request that a VPN provider
+// show its "add network" dialog.
+class ASH_EXPORT VPNDelegate {
+ public:
+  // An observer that is notified whenever the list of third-party VPN providers
+  // enabled in the primary user's profile changes.
+  class Observer {
+   public:
+    virtual void OnThirdPartyVPNProvidersChanged() = 0;
+
+   protected:
+    virtual ~Observer();
+
+   private:
+    DISALLOW_ASSIGN(Observer);
+  };
+
+  VPNDelegate();
+  virtual ~VPNDelegate();
+
+  // Returns |true| if at least one third-party VPN provider is enabled in the
+  // primary user's profile.
+  virtual bool HaveThirdPartyVPNProviders() const = 0;
+
+  // Returns the list of third-party VPN providers enabled in the primary user's
+  // profile.
+  virtual std::vector<VPNProvider> GetThirdPartyVPNProviders() const = 0;
+
+  // Requests that the VPN provider identified by |id| show its "add network"
+  // dialog. If |id| is an empty string, the built-in dialog for adding an
+  // OpenVPN or L2TP VPN is shown.
+  virtual void ShowAddPage(const std::string& id) = 0;
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+ protected:
+  // Notify observers that the list of third-party VPN providers enabled in the
+  // primary user's profile has changed.
+  void NotifyObservers();
+
+ private:
+  ObserverList<Observer, true> observer_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(VPNDelegate);
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_CHROMEOS_NETWORK_VPN_DELEGATE_H