[iOS Clean] Created OverlayService.

ios/clean/chrome/browser/ui/overlays/web_state_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_OVERLAYS_WEB_STATE_OVERLAY_QUEUE_H_
+#define IOS_CLEAN_CHROME_BROWSER_UI_OVERLAYS_WEB_STATE_OVERLAY_QUEUE_H_
+
+#import "ios/clean/chrome/browser/ui/overlays/overlay_queue.h"
+#import "ios/web/public/web_state/web_state_user_data.h"
+
+// An implementation of OverlayQueue that stores BrowserCoordinators for a
+// specific WebState.
+class WebStateOverlayQueue
+    : public OverlayQueue,
+      public web::WebStateUserData<WebStateOverlayQueue> {
+ public:
+  // OverlayQueue:
+  web::WebState* GetWebState() const override;
+  void StartNextOverlay() override;
+
+  // Adds an overlay coordinator that will be displayed over GetWebState()'s
+  // content area.
+  void AddWebStateOverlay(BrowserCoordinator* overlay_coordinator);
+  // Sets the parent coordinator to use for queued BrowserCoordinators.
+  // |parent| is expected to be displaying GetWebState()'s content area before
+  // calling this function.
+  void SetWebStateParentCoordinator(BrowserCoordinator* parent_coordinator);
+
+ private:
+  friend class web::WebStateUserData<WebStateOverlayQueue>;
+  // The WebState with which this presenter is associated.
+  web::WebState* web_state_;
+  // The parent coordinator to use for overlays.
+  BrowserCoordinator* parent_coordinator_;

[marq (ping after 24h), 2017/06/21 09:41:54]

_weak, I'm guessing; default would be strong.

[kkhorimoto, 2017/06/23 06:11:16]

Done.

+
+  // Private constructor.
+  explicit WebStateOverlayQueue(web::WebState* web_state);
+
+  DISALLOW_COPY_AND_ASSIGN(WebStateOverlayQueue);
+};
+
+#endif  // IOS_CLEAN_CHROME_BROWSER_UI_OVERLAYS_WEB_STATE_OVERLAY_QUEUE_H_