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..b614ce2a1a520b5420f616011753f74f21f1a3b9
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+++ b/ash/system/chromeos/network/vpn_delegate.h
@@ -0,0 +1,101 @@
+// 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 chromeos {
+class NetworkState;
+}
+
+namespace ash {
+
+// Describes a VPN provider.
+struct ASH_EXPORT VPNProvider {
+  struct Key {
+    // Constructs a key for the built-in VPN provider.
+    Key();
+
+    // Constructs a key for a third-party VPN provider.
+    explicit Key(const std::string& extension_id);
+
+    bool operator==(const Key& other) const;
+
+    // Indicates whether |network| belongs to this VPN provider.
+    bool MatchesNetwork(const chromeos::NetworkState& network) const;
+
+    // Whether this key represents a built-in or third-party VPN provider.
+    bool third_party;
+
+    // ID of the extension that implements this provider. Used for third-party
+    // VPN providers only.
+    std::string extension_id;
+  };
+
+  VPNProvider(const Key& key, const std::string& name);
+
+  // Key that uniquely identifies this VPN provider.
+  Key key;
+
+  // Human-readable name.
+  std::string name;
+};
+
+// This delegate provides UI code in ash, e.g. |VPNList|, with access to the
+// list of 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 VPN providers enabled in
+  // the primary user's profile changes.
+  class Observer {
+   public:
+    virtual void OnVPNProvidersChanged() = 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, in addition to the built-in OpenVPN/L2TP provider.
+  virtual bool HaveThirdPartyVPNProviders() const = 0;
+
+  // Returns the list of VPN providers enabled in the primary user's profile.
+  virtual const std::vector<VPNProvider>& GetVPNProviders() const = 0;
+
+  // Requests that the VPN provider identified by |key| show its "add network"
+  // dialog.
+  virtual void ShowAddPage(const VPNProvider::Key& key) = 0;
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+ protected:
+  // Notify observers that the list of 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