fix(menu): not closing when overlay is detached externally (#8654)

Fixes the menu panel not being closed when its `OverlayRef` is detached externally using `detach`, for example when using the `CloseScrollStrategy`.

src/lib/menu/menu-directive.ts

@@ -187,7 +187,6 @@ export class MatMenu implements AfterContentInit, MatMenuPanel, OnDestroy {
 
   ngOnDestroy() {
     this._tabSubscription.unsubscribe();
-    this.closed.emit();
     this.closed.complete();
   }
 

src/lib/menu/menu-trigger.ts

@@ -193,9 +193,7 @@ export class MatMenuTrigger implements AfterContentInit, OnDestroy {
   openMenu(): void {
     if (!this._menuOpen) {
       this._createOverlay().attach(this._portal);
-      this._closeSubscription = this._menuClosingActions().subscribe(() => {
-        this.menu.close.emit();
-      });
+      this._closeSubscription = this._menuClosingActions().subscribe(() => this.closeMenu());
       this._initMenu();
 
       if (this.menu instanceof MatMenu) {
@@ -218,8 +216,8 @@ export class MatMenuTrigger implements AfterContentInit, OnDestroy {
   private _destroyMenu() {
     if (this._overlayRef && this.menuOpen) {
       this._resetMenu();
-      this._overlayRef.detach();
       this._closeSubscription.unsubscribe();
+      this._overlayRef.detach();
 
       if (this.menu instanceof MatMenu) {
         this.menu._resetAnimation();
@@ -400,13 +398,14 @@ export class MatMenuTrigger implements AfterContentInit, OnDestroy {
   /** Returns a stream that emits whenever an action that should close the menu occurs. */
   private _menuClosingActions() {
     const backdrop = this._overlayRef!.backdropClick();
+    const detachments = this._overlayRef!.detachments();
     const parentClose = this._parentMenu ? this._parentMenu.close : observableOf();
     const hover = this._parentMenu ? this._parentMenu._hovered().pipe(
       filter(active => active !== this._menuItemInstance),
       filter(() => this._menuOpen)
     ) : observableOf();
 
-    return merge(backdrop, parentClose, hover);
+    return merge(backdrop, parentClose, hover, detachments);
   }
 
   /** Handles mouse presses on the trigger. */

src/lib/menu/menu.spec.ts

@@ -13,7 +13,7 @@ import {
   QueryList,
 } from '@angular/core';
 import {Direction, Directionality} from '@angular/cdk/bidi';
-import {OverlayContainer} from '@angular/cdk/overlay';
+import {OverlayContainer, Overlay} from '@angular/cdk/overlay';
 import {ESCAPE, LEFT_ARROW, RIGHT_ARROW} from '@angular/cdk/keycodes';
 import {
   MAT_MENU_DEFAULT_OPTIONS,
@@ -25,7 +25,7 @@ import {
   MenuPositionY,
   MatMenuItem,
 } from './index';
-import {MENU_PANEL_TOP_PADDING} from './menu-trigger';
+import {MENU_PANEL_TOP_PADDING, MAT_MENU_SCROLL_STRATEGY} from './menu-trigger';
 import {MatRipple} from '@angular/material/core';
 import {
   dispatchKeyboardEvent,
@@ -35,6 +35,8 @@ import {
   createMouseEvent,
   dispatchFakeEvent,
 } from '@angular/cdk/testing';
+import {Subject} from 'rxjs/Subject';
+import {ScrollDispatcher} from '@angular/cdk/scrolling';
 
 
 describe('MatMenu', () => {
@@ -242,6 +244,34 @@ describe('MatMenu', () => {
     expect(document.activeElement).toBe(panel, 'Expected the panel to be focused.');
   });
 
+  it('should close the menu when using the CloseScrollStrategy', fakeAsync(() => {
+    const scrolledSubject = new Subject();
+
+    TestBed.overrideProvider(ScrollDispatcher, {
+      deps: [],
+      useFactory: () => ({scrolled: () => scrolledSubject})
+    });
+
+    TestBed.overrideProvider(MAT_MENU_SCROLL_STRATEGY, {
+      deps: [Overlay],
+      useFactory: (overlay: Overlay) => () => overlay.scrollStrategies.close()
+    });
+
+    const fixture = TestBed.createComponent(SimpleMenu);
+    const trigger = fixture.componentInstance.trigger;
+
+    fixture.detectChanges();
+    trigger.openMenu();
+    fixture.detectChanges();
+
+    expect(trigger.menuOpen).toBe(true);
+
+    scrolledSubject.next();
+    tick(500);
+
+    expect(trigger.menuOpen).toBe(false);
+  }));
+
   describe('positions', () => {
     let fixture: ComponentFixture<PositionedMenu>;
     let panel: HTMLElement;