Add ash::VPNDelegate and Chrome OS implementation

chrome/browser/ui/ash/vpn_delegate_chromeos.h

+// 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 CHROME_BROWSER_UI_ASH_VPN_DELEGATE_CHROMEOS_H_
+#define CHROME_BROWSER_UI_ASH_VPN_DELEGATE_CHROMEOS_H_
+
+#include <vector>
+
+#include "ash/system/chromeos/network/vpn_delegate.h"
+#include "base/macros.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "extensions/browser/extension_registry_observer.h"
+
+namespace extensions {
+class ExtensionRegistry;
+}
+
+// Chrome OS implementation of a delegate that provides UI code in ash with
+// access to the VPN providers enabled in the primary user's profile.
+class VPNDelegateChromeOS : public ash::VPNDelegate,
+                            public extensions::ExtensionRegistryObserver,
+                            public content::NotificationObserver {
+ public:
+  VPNDelegateChromeOS();
+  ~VPNDelegateChromeOS() override;
+
+  // ash::VPNDelegate:
+  bool HaveThirdPartyVPNProviders() const override;
+  const std::vector<ash::VPNProvider>& GetVPNProviders() const override;
+  void ShowAddPage(const std::string& id) override;
+
+  // extensions::ExtensionRegistryObserver:
+  void OnExtensionLoaded(content::BrowserContext* browser_context,
+                         const extensions::Extension* extension) override;
+  void OnExtensionUnloaded(
+      content::BrowserContext* browser_context,
+      const extensions::Extension* extension,
+      extensions::UnloadedExtensionInfo::Reason reason) override;
+  void OnShutdown(extensions::ExtensionRegistry* registry) override;
+
+  // content::NotificationObserver:
+  void Observe(int type,
+               const content::NotificationSource& source,
+               const content::NotificationDetails& details) override;
+
+ private:
+  // Retrieves the current list of VPN providers enabled in the primary user's
+  // profile and notifies observers that it has changed. Must only be called
+  // when a user is logged in and the primary user's extension registry is being
+  // observed.
+  void UpdateVPNProviders();
+
+  // Starts observing the primary user's extension registry to detect changes to
+  // the list of VPN providers enabled in the user's profile and caches the
+  // initial list. Must only be called when a user is logged in.
+  void AttachToPrimaryUserExtensionRegistry();
+
+  // The primary user's extension registry, if a user is logged in.
+  extensions::ExtensionRegistry* extension_registry_ = nullptr;
+
+  // A cache of the VPN providers enabled in the primary user's profile.
+  std::vector<ash::VPNProvider> vpn_providers_;
+
+  content::NotificationRegistrar registrar_;
+
+  DISALLOW_COPY_AND_ASSIGN(VPNDelegateChromeOS);
+};
+
+#endif  // CHROME_BROWSER_UI_ASH_VPN_DELEGATE_CHROMEOS_H_