[iOS Clean] Created OverlayService.

ios/clean/chrome/browser/ui/overlays/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/overlays/overlay_queue.h"
+
+#include "base/logging.h"
+#import "ios/clean/chrome/browser/ui/commands/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(OverlayQueue);
+
+// static
+void OverlayQueue::CreateForWebState(web::WebState* web_state,
+                                     id<OverlaySchedulerCommands> dispatcher) {
+  DCHECK(web_state);
+  DCHECK(dispatcher);
+  if (!FromWebState(web_state)) {
+    std::unique_ptr<OverlayQueue> queue =
+        base::WrapUnique(new OverlayQueue(web_state, dispatcher));
+    web_state->SetUserData(UserDataKey(), std::move(queue));
+  }
+}
+
+OverlayQueue::OverlayQueue(web::WebState* web_state,
+                           id<OverlaySchedulerCommands> dispatcher)
+    : web_state_(web_state),
+      dispatcher_(dispatcher),
+      overlays_([[NSMutableArray alloc] init]),
+      showing_overlay_(false) {
+  DCHECK(web_state);
+  DCHECK(dispatcher);
+}
+
+OverlayQueue::~OverlayQueue() {
+  [dispatcher_ cancelOverlaysForWebState:web_state_];
+}
+
+void OverlayQueue::AddOverlay(OverlayCoordinator* overlay_coordinator) {
+  // Add the overlay coordinator to the queue, then notify the scheduler.
+  DCHECK(overlay_coordinator);
+  [overlays_ addObject:overlay_coordinator];
+  [dispatcher_ scheduleOverlayForWebState:web_state_];
+}
+
+void OverlayQueue::ReplaceVisibleOverlay(
+    OverlayCoordinator* overlay_coordinator) {
+  DCHECK(overlay_coordinator);
+  DCHECK(IsShowingOverlay());
+  DCHECK_GE([overlays_ count], 1U);
+  // Add the overlay after the currently displayed overlay and notify the
+  // scheduler that the overlay was replaced.  Stopping the front overlay below
+  // will cause |overlay_cordinator| to start.
+  [overlays_ insertObject:overlay_coordinator atIndex:1];
+  [dispatcher_ visibleOverlayWasReplacedForWebState:web_state_];
+  OverlayCoordinator* visible_overlay = [overlays_ firstObject];
+  [visible_overlay cancelOverlay];
+  [visible_overlay stop];
+}
+
+bool OverlayQueue::HasQueuedOverlays() const {
+  return [overlays_ count] > 0U;
+}
+
+void OverlayQueue::StartNextOverlay(BrowserCoordinator* web_coordinator) {
+  DCHECK(web_coordinator);
+  DCHECK(HasQueuedOverlays());
+  DCHECK(!IsShowingOverlay());
+  [[overlays_ firstObject] startOverlayingCoordinator:web_coordinator];
+  showing_overlay_ = true;
+}
+
+bool OverlayQueue::IsShowingOverlay() const {
+  return showing_overlay_;
+}
+
+void OverlayQueue::OverlayWasStopped(OverlayCoordinator* overlay_coordinator) {
+  DCHECK(overlay_coordinator);
+  DCHECK_EQ([overlays_ firstObject], overlay_coordinator);
+  DCHECK(showing_overlay_);
+  [overlays_ removeObjectAtIndex:0];
+  showing_overlay_ = false;
+  [dispatcher_ overlayWasStoppedForWebState:web_state_];
+}
+
+void OverlayQueue::CancelOverlays() {
+  // Call the WebKit completion blocks for all queued overlays.
+  for (OverlayCoordinator* overlay_coordinator in overlays_) {
+    [overlay_coordinator cancelOverlay];
+  }
+  // Remove the queued overlays and stop the visible overlay if one is
+  // presented.  Stopping the visible overlay will trigger the next scheduled
+  // overlay, so the queue should be emptied before calling |-stop|.
+  OverlayCoordinator* visible_overlay =
+      showing_overlay_ ? [overlays_ firstObject] : nil;
+  [overlays_ removeAllObjects];
+  [visible_overlay stop];
+}