[iOS Clean] Created OverlayService.

ios/clean/chrome/browser/ui/overlay_service/internal/web_state_overlay_queue.h

Index: ios/clean/chrome/browser/ui/overlay_service/internal/web_state_overlay_queue.h
diff --git a/ios/clean/chrome/browser/ui/overlay_service/internal/web_state_overlay_queue.h b/ios/clean/chrome/browser/ui/overlay_service/internal/web_state_overlay_queue.h
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index 0000000000000000000000000000000000000000..45b26429ba684c7255c0027254d52a8ac7b3b67f
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+++ b/ios/clean/chrome/browser/ui/overlay_service/internal/web_state_overlay_queue.h
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+// 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_INTERNAL_WEB_STATE_OVERLAY_QUEUE_H_
+#define IOS_CLEAN_CHROME_BROWSER_UI_OVERLAYS_INTERNAL_WEB_STATE_OVERLAY_QUEUE_H_
+
+#import "ios/clean/chrome/browser/ui/overlay_service/internal/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.
+  __weak BrowserCoordinator* parent_coordinator_;
+
+  // Private constructor.
+  explicit WebStateOverlayQueue(web::WebState* web_state);
+
+  DISALLOW_COPY_AND_ASSIGN(WebStateOverlayQueue);
+};
+
+#endif  // IOS_CLEAN_CHROME_BROWSER_UI_OVERLAYS_INTERNAL_WEB_STATE_OVERLAY_QUEUE_H_