[iOS Clean] Created OverlayService.

ios/clean/chrome/browser/ui/web_contents/overlays/web_overlay_queue.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_CLEAN_CHROME_BROWSER_UI_WEB_CONTENTS_OVERLAYS_WEB_OVERLAY_QUEUE_H_
+#define IOS_CLEAN_CHROME_BROWSER_UI_WEB_CONTENTS_OVERLAYS_WEB_OVERLAY_QUEUE_H_
+
+#import <Foundation/Foundation.h>
+
+#include "base/ios/weak_nsobject.h"
+#import "base/mac/scoped_nsobject.h"
+#import "ios/clean/chrome/browser/ui/web_contents/overlays/web_overlay_coordinator.h"
+#import "ios/web/public/web_state/web_state_user_data.h"
+
+@protocol WebOverlaySchedulerCommands;
+
+// Class used to enqueue overlay coordinators that are requested by a WebState.
+// It uses WebOverlaySchedulerCommands to communicate with WebOverlayScheduler
+// to decide when to display the overlay UI.
+class WebOverlayQueue : public web::WebStateUserData<WebOverlayQueue> {
+ public:
+  ~WebOverlayQueue() override;
+
+  // Factory method that instantaites a WebOverlayQueue for |web_state| that
+  // uses |dispatcher| to send overlay scheduling commands.
+  static void CreateForWebState(web::WebState* web_state,
+                                id<WebOverlaySchedulerCommands> dispatcher);
+
+  // Adds |web_overlay| to the queue and schedules its presentation.
+  void AddWebOverlay(WebOverlayCoordinator* overlay_coordinator);
+  // Returns whether there are any queued overlays.
+  bool HasQueuedOverlays() const;
+  // Displays the next overlay over |web_coordinator|'s UI.  |web_coordinator|
+  // is expected to be displaying the web view that requested the overlay.
+  void StartNextOverlay(BrowserCoordinator* web_coordinator);
+  // Returns whether an overlay is curently started.
+  bool IsShowingOverlay() const;
+  // Notifies the WebOverlayQueue that |overlay_coordinator| was stopped.
+  void WebOverlayWasStopped(WebOverlayCoordinator* overlay_coordinator);
+  // Cancels all queued overlays for this WebState.  If one is being displayed,
+  // it will be stopped and cancelled.
+  void CancelOverlays();
+
+ private:
+  friend class web::WebStateUserData<WebOverlayQueue>;
+  // The WebState with which this presenter is associated.
+  web::WebState* web_state_;
+  // The WebOverlayScheduler dispatcher passed on construction.
+  base::WeakNSProtocol<id<WebOverlaySchedulerCommands>> dispatcher_;
+  // The queue of overlays that were added for this WebState.  Overlays will be
+  // removed when they are stopped or when they
+  base::scoped_nsobject<NSMutableArray<WebOverlayCoordinator*>> overlays_;
+  // Whether the first overlay in |overlays_| is started.
+  bool showing_overlay_;
+
+  // Private constructor.  New instances should be created via
+  // CreateForWebState() and accessed via FromWebState().
+  explicit WebOverlayQueue(web::WebState* web_state,
+                           id<WebOverlaySchedulerCommands> dispatcher);
+
+  DISALLOW_COPY_AND_ASSIGN(WebOverlayQueue);
+};
+#endif  // IOS_CLEAN_CHROME_BROWSER_UI_WEB_CONTENTS_OVERLAYS_WEB_OVERLAY_QUEUE_H_