[iOS Clean] Created OverlayService.

ios/clean/chrome/browser/ui/web_contents/overlays/web_overlay_queue.mm

+// 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.
+
+#import "ios/clean/chrome/browser/ui/web_contents/overlays/web_overlay_queue.h"
+
+#include "base/logging.h"
+#import "ios/clean/chrome/browser/ui/commands/web_overlay_commands.h"
+#import "ios/shared/chrome/browser/ui/coordinators/browser_coordinator.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+DEFINE_WEB_STATE_USER_DATA_KEY(WebOverlayQueue);
+
+// static
+void WebOverlayQueue::CreateForWebState(
+    web::WebState* web_state,
+    id<WebOverlaySchedulerCommands> dispatcher) {
+  DCHECK(web_state);
+  DCHECK(dispatcher);
+  if (!FromWebState(web_state)) {
+    std::unique_ptr<WebOverlayQueue> queue =
+        base::WrapUnique(new WebOverlayQueue(web_state, dispatcher));
+    web_state->SetUserData(UserDataKey(), std::move(queue));
+  }
+}
+
+WebOverlayQueue::WebOverlayQueue(web::WebState* web_state,
+                                 id<WebOverlaySchedulerCommands> dispatcher)
+    : web_state_(web_state),
+      dispatcher_(dispatcher),
+      overlays_([[NSMutableArray alloc] init]),
+      showing_overlay_(false) {
+  DCHECK(web_state);
+  DCHECK(dispatcher);
+}
+
+WebOverlayQueue::~WebOverlayQueue() {}
+
+void WebOverlayQueue::AddWebOverlay(
+    WebOverlayCoordinator* overlay_coordinator) {
+  // Add the overlay coordinator to the queue, then notify the scheduler.
+  DCHECK(overlay_coordinator);
+  [overlays_ addObject:overlay_coordinator];
+  [dispatcher_ scheduleWebOverlayForWebState:web_state_];
+}
+
+bool WebOverlayQueue::HasQueuedOverlays() const {
+  return [overlays_ count] > 0U;
+}
+
+void WebOverlayQueue::StartNextOverlay(BrowserCoordinator* web_coordinator) {
+  DCHECK(web_coordinator);
+  DCHECK(HasQueuedOverlays());
+  DCHECK(!IsShowingOverlay());
+  [[overlays_ firstObject] startOverlayingWebCoordinator:web_coordinator];
+  showing_overlay_ = true;
+}
+
+bool WebOverlayQueue::IsShowingOverlay() const {
+  return showing_overlay_;
+}
+
+void WebOverlayQueue::WebOverlayWasStopped(
+    WebOverlayCoordinator* overlay_coordinator) {
+  DCHECK(overlay_coordinator);
+  DCHECK_EQ([overlays_ firstObject], overlay_coordinator);
+  DCHECK(showing_overlay_);
+  [overlays_ removeObjectAtIndex:0];
+  showing_overlay_ = false;
+}
+
+void WebOverlayQueue::CancelOverlays() {
+  // Call the WebKit completion blocks for all queued overlays.
+  for (WebOverlayCoordinator* overlay_coordinator in overlays_.get()) {
+    [overlay_coordinator cancelWebKitCompletion];
+  }
+  // Stop the currently visible one, if necessary.
+  if (showing_overlay_)
+    [[overlays_ firstObject] stop];
+  // Empty the queue.
+  [overlays_ removeAllObjects];
+}