cros: Enable WebUILoginView reuse.

chrome/browser/chromeos/login/ui/web_view_handle.h

+// Copyright 2016 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_CHROMEOS_LOGIN_UI_WEB_VIEW_HANDLE_H_
+#define CHROME_BROWSER_CHROMEOS_LOGIN_UI_WEB_VIEW_HANDLE_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+
+class Profile;
+
+namespace views {
+class WebView;
+}
+
+namespace chromeos {
+
+// Owns a views::WebView instance. Any caller actively using the views::WebView
+// instance should increase/decrease the refcount.
+class WebViewHandle : public base::RefCounted<WebViewHandle> {
+ public:
+  explicit WebViewHandle(Profile* profile);
+
+  // Returns an unowned pointer to the stored |web_view| instance.
+  views::WebView* web_view() { return web_view_.get(); }
+
+ private:
+  friend class base::RefCounted<WebViewHandle>;
+  ~WebViewHandle();
+
+  std::unique_ptr<views::WebView> web_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebViewHandle);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_UI_WEB_VIEW_HANDLE_H_