fix(overlay): CloseScrollStrategy not triggering change detection on close (#7929)

After some refactoring, the `ScrollDispatcher` no longer dispatches inside the `NgZone`, which caused the `CloseScrollStrategy` to break, because it detaches without triggering change detection. These changes bring the detachment back into the `NgZone`.

Fixes #7922.

Author: crisbeto

src/cdk/overlay/scroll/close-scroll-strategy.spec.ts

@@ -1,5 +1,5 @@
 import {inject, TestBed, async} from '@angular/core/testing';
-import {NgModule, Component} from '@angular/core';
+import {NgModule, Component, NgZone} from '@angular/core';
 import {Subject} from 'rxjs/Subject';
 import {ComponentPortal, PortalModule} from '@angular/cdk/portal';
 import {ScrollDispatcher} from '@angular/cdk/scrolling';
@@ -59,6 +59,17 @@ describe('CloseScrollStrategy', () => {
     expect(overlayRef.detach).not.toHaveBeenCalled();
   });
 
+  it('should detach inside the NgZone', () => {
+    const spy = jasmine.createSpy('detachment spy');
+    const subscription = overlayRef.detachments().subscribe(() => spy(NgZone.isInAngularZone()));
+
+    overlayRef.attach(componentPortal);
+    scrolledSubject.next();
+
+    expect(spy).toHaveBeenCalledWith(true);
+    subscription.unsubscribe();
+  });
+
 });
 
 

src/cdk/overlay/scroll/close-scroll-strategy.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {NgZone} from '@angular/core';
 import {ScrollStrategy, getMatScrollStrategyAlreadyAttachedError} from './scroll-strategy';
 import {OverlayRef} from '../overlay-ref';
 import {Subscription} from 'rxjs/Subscription';
@@ -19,7 +20,7 @@ export class CloseScrollStrategy implements ScrollStrategy {
   private _scrollSubscription: Subscription|null = null;
   private _overlayRef: OverlayRef;
 
-  constructor(private _scrollDispatcher: ScrollDispatcher) { }
+  constructor(private _scrollDispatcher: ScrollDispatcher, private _ngZone: NgZone) { }
 
   /** Attaches this scroll strategy to an overlay. */
   attach(overlayRef: OverlayRef) {
@@ -34,11 +35,13 @@ export class CloseScrollStrategy implements ScrollStrategy {
   enable() {
     if (!this._scrollSubscription) {
       this._scrollSubscription = this._scrollDispatcher.scrolled(0).subscribe(() => {
-        if (this._overlayRef.hasAttached()) {
-          this._overlayRef.detach();
-        }
+        this._ngZone.run(() => {
+          this.disable();
 
-        this.disable();
+          if (this._overlayRef.hasAttached()) {
+            this._overlayRef.detach();
+          }
+        });
       });
     }
   }

src/cdk/overlay/scroll/scroll-strategy-options.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {Injectable} from '@angular/core';
+import {Injectable, NgZone} from '@angular/core';
 import {CloseScrollStrategy} from './close-scroll-strategy';
 import {NoopScrollStrategy} from './noop-scroll-strategy';
 import {BlockScrollStrategy} from './block-scroll-strategy';
@@ -28,13 +28,14 @@ import {
 export class ScrollStrategyOptions {
   constructor(
     private _scrollDispatcher: ScrollDispatcher,
-    private _viewportRuler: ViewportRuler) { }
+    private _viewportRuler: ViewportRuler,
+    private _ngZone: NgZone) { }
 
   /** Do nothing on scroll. */
   noop = () => new NoopScrollStrategy();
 
   /** Close the overlay as soon as the user scrolls. */
-  close = () => new CloseScrollStrategy(this._scrollDispatcher);
+  close = () => new CloseScrollStrategy(this._scrollDispatcher, this._ngZone);
 
   /** Block scrolling. */
   block = () => new BlockScrollStrategy(this._viewportRuler);