fix(drag-drop): drop list not toggling dragging class inside component with OnPush change detection

Fixes the `CdkDropList` not toggling its `cdk-drop-list-dragging` class if it's placed inside a component with `OnPush` change detection.

Fixes #13680.

Author: crisbeto

src/cdk/drag-drop/drag.spec.ts

@@ -9,6 +9,7 @@ import {
   ViewChild,
   ViewChildren,
   ViewEncapsulation,
+  ChangeDetectionStrategy,
 } from '@angular/core';
 import {TestBed, ComponentFixture, fakeAsync, flush, tick} from '@angular/core/testing';
 import {DragDropModule} from './drag-drop-module';
@@ -533,6 +534,27 @@ describe('CdkDrag', () => {
       expect(dropZone.element.nativeElement.classList).not.toContain('cdk-drop-dragging');
     }));
 
+    it('should toggle a class when the user starts dragging an item with OnPush change detection',
+      fakeAsync(() => {
+        const fixture = createComponent(DraggableInOnPushDropZone);
+        fixture.detectChanges();
+        const item = fixture.componentInstance.dragItems.toArray()[1].element.nativeElement;
+        const dropZone = fixture.componentInstance.dropInstance;
+
+        expect(dropZone.element.nativeElement.classList).not.toContain('cdk-drop-list-dragging');
+
+        startDraggingViaMouse(fixture, item);
+
+        expect(dropZone.element.nativeElement.classList).toContain('cdk-drop-list-dragging');
+
+        dispatchMouseEvent(document, 'mouseup');
+        fixture.detectChanges();
+        flush();
+        fixture.detectChanges();
+
+        expect(dropZone.element.nativeElement.classList).not.toContain('cdk-drop-dragging');
+      }));
+
     it('should not toggle dragging class if the element was not dragged more than the threshold',
       fakeAsync(() => {
         const fixture = createComponent(DraggableInDropZone, [], 5);
@@ -1807,22 +1829,22 @@ class StandaloneDraggableWithMultipleHandles {
   @ViewChildren(CdkDragHandle) handles: QueryList<CdkDragHandle>;
 }
 
-@Component({
-  template: `
-    <div
-      cdkDropList
-      style="width: 100px; background: pink;"
-      [id]="dropZoneId"
-      [cdkDropListData]="items"
-      (cdkDropListDropped)="droppedSpy($event)">
-      <div
-        *ngFor="let item of items"
-        cdkDrag
-        [cdkDragData]="item"
-        style="width: 100%; height: ${ITEM_HEIGHT}px; background: red;">{{item}}</div>
-    </div>
-  `
-})
+const DROP_ZONE_FIXTURE_TEMPLATE = `
+<div
+  cdkDropList
+  style="width: 100px; background: pink;"
+  [id]="dropZoneId"
+  [cdkDropListData]="items"
+  (cdkDropListDropped)="droppedSpy($event)">
+  <div
+    *ngFor="let item of items"
+    cdkDrag
+    [cdkDragData]="item"
+    style="width: 100%; height: ${ITEM_HEIGHT}px; background: red;">{{item}}</div>
+</div>
+`;
+
+@Component({template: DROP_ZONE_FIXTURE_TEMPLATE})
 class DraggableInDropZone {
   @ViewChildren(CdkDrag) dragItems: QueryList<CdkDrag>;
   @ViewChild(CdkDropList) dropInstance: CdkDropList;
@@ -1833,6 +1855,12 @@ class DraggableInDropZone {
   });
 }
 
+@Component({
+  template: DROP_ZONE_FIXTURE_TEMPLATE,
+  changeDetection: ChangeDetectionStrategy.OnPush,
+})
+class DraggableInOnPushDropZone extends DraggableInDropZone {}
+
 
 @Component({
   encapsulation: ViewEncapsulation.None,

src/cdk/drag-drop/drag.ts

@@ -28,7 +28,7 @@ import {
   SkipSelf,
   ViewContainerRef,
 } from '@angular/core';
-import {supportsPassiveEventListeners} from '@angular/cdk/platform';
+import {normalizePassiveListenerOptions} from '@angular/cdk/platform';
 import {Observable, Subject, Subscription, Observer} from 'rxjs';
 import {take} from 'rxjs/operators';
 import {DragDropRegistry} from './drag-drop-registry';
@@ -80,8 +80,7 @@ export function CDK_DRAG_CONFIG_FACTORY(): CdkDragConfig {
 }
 
 /** Options that can be used to bind a passive event listener. */
-const passiveEventListenerOptions = supportsPassiveEventListeners() ?
-    {passive: true} as EventListenerOptions : false;
+const passiveEventListenerOptions = normalizePassiveListenerOptions({passive: true});
 
 /** Element that can be moved inside a CdkDropList container. */
 @Directive({

src/cdk/drag-drop/drop-list.ts

@@ -19,6 +19,7 @@ import {
   QueryList,
   Optional,
   Directive,
+  ChangeDetectorRef,
 } from '@angular/core';
 import {Directionality} from '@angular/cdk/bidi';
 import {CdkDrag} from './drag';
@@ -104,6 +105,7 @@ export class CdkDropList<T = any> implements OnInit, OnDestroy {
   constructor(
     public element: ElementRef<HTMLElement>,
     private _dragDropRegistry: DragDropRegistry<CdkDrag, CdkDropList<T>>,
+    private _changeDetectorRef: ChangeDetectorRef,
     @Optional() private _dir?: Directionality) {}
 
   ngOnInit() {
@@ -142,6 +144,7 @@ export class CdkDropList<T = any> implements OnInit, OnDestroy {
     this._dragging = true;
     this._activeDraggables = this._draggables.toArray();
     this._cachePositions();
+    this._changeDetectorRef.markForCheck();
   }
 
   /**