Implemented FormResubmissionTabHelper.

ios/chrome/browser/web/form_resubmission_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_FORM_RESUBMISSION_TAB_HELPER_H_
+#define IOS_CHROME_BROWSER_WEB_FORM_RESUBMISSION_TAB_HELPER_H_
+
+#include <CoreGraphics/CoreGraphics.h>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#import "base/mac/scoped_nsobject.h"
+#include "ios/web/public/web_state/web_state_observer.h"
+#import "ios/web/public/web_state/web_state_user_data.h"
+
+@class FormResubmissionCoordinator;
+
+// Allows presenting form resubmission dialog. Listens to web::WebState activity
+// and dismisses the dialog when necessary.
+class FormResubmissionTabHelper
+    : public web::WebStateUserData<FormResubmissionTabHelper>,
+      public web::WebStateObserver {
+ public:
+  explicit FormResubmissionTabHelper(web::WebState* web_state);
+  ~FormResubmissionTabHelper() override;
+
+  // Presents Form Resubmission Dialog at the given |location|. |callback| is
+  // called with true if resubmission was confirmed and with false if it was
+  // cancelled.
+  void PresentFormResubmissionDialog(
+      CGPoint location,
+      const base::Callback<void(bool)>& callback);
+
+ private:
+  // web::WebStateObserver overrides:
+  void ProvisionalNavigationStarted(const GURL&) override;
+  void WebStateDestroyed() override;
+
+  // Coordinates Form Resubmission dialog presentation.
+  base::scoped_nsobject<FormResubmissionCoordinator> coordinator_;
+
+  DISALLOW_COPY_AND_ASSIGN(FormResubmissionTabHelper);
+};
+
+#endif  // IOS_CHROME_BROWSER_WEB_FORM_RESUBMISSION_TAB_HELPER_H_