[ios] TabIdTabHelper

ios/chrome/browser/web/tab_id_tab_helper.h

+// Copyright 2017 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 IOS_CHROME_BROWSER_WEB_TAB_ID_TAB_HELPER_H_
+#define IOS_CHROME_BROWSER_WEB_TAB_ID_TAB_HELPER_H_
+
+#include "base/macros.h"
+#import "ios/web/public/web_state/web_state_user_data.h"
+
+// Handles creating a unique identifier, which is stable across cold starts.
+class TabIdTabHelper : public web::WebStateUserData<TabIdTabHelper> {
+ public:
+  ~TabIdTabHelper() override;
+
+  // Returns a unique identifier for this tab.
+  NSString* tab_id() const { return tab_id_; }
+
+ private:
+  friend class web::WebStateUserData<TabIdTabHelper>;
+  explicit TabIdTabHelper(web::WebState* web_state);
+  __strong NSString* tab_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(TabIdTabHelper);
+};
+
+#endif  // IOS_CHROME_BROWSER_WEB_TAB_ID_TAB_HELPER_H_