fix(autocomplete): not closing when clicking outside while propagation is stopped

Fixes the autocomplete panel not closing if the user clicks outside on an element that stops propagation of the `click` event (e.g. a `mat-chip`).

Fixes #17352.

Author: crisbeto

src/material/autocomplete/autocomplete-trigger.ts

@@ -350,9 +350,11 @@ export class MatAutocompleteTrigger implements ControlValueAccessor, AfterViewIn
 
   /** Stream of clicks outside of the autocomplete panel. */
   private _getOutsideClickStream(): Observable<any> {
+    // Use capturing so we can close even if propagation is stopped.
+    const eventOptions = {capture: true};
     return merge(
-               fromEvent(this._document, 'click') as Observable<MouseEvent>,
-               fromEvent(this._document, 'touchend') as Observable<TouchEvent>)
+               fromEvent(this._document, 'click', eventOptions) as Observable<MouseEvent>,
+               fromEvent(this._document, 'touchend', eventOptions) as Observable<TouchEvent>)
         .pipe(filter(event => {
           // If we're in the Shadow DOM, the event target will be the shadow root, so we have to
           // fall back to check the first element in the path of the click event.

src/material/autocomplete/autocomplete.spec.ts

@@ -188,6 +188,20 @@ describe('MatAutocomplete', () => {
           .toEqual('', `Expected clicking outside the panel to close the panel.`);
     }));
 
+    it('should close the panel when clicking away and propagation is stopped', fakeAsync(() => {
+      const trigger = fixture.componentInstance.trigger;
+      dispatchFakeEvent(input, 'focusin');
+      fixture.detectChanges();
+      zone.simulateZoneExit();
+
+      expect(trigger.panelOpen).toBe(true, 'Expected panel to be open.');
+
+      fixture.nativeElement.querySelector('.stop-propagation').click();
+      fixture.detectChanges();
+
+      expect(trigger.panelOpen).toBe(false, 'Expected panel to be closed.');
+    }));
+
     it('should close the panel when the user taps away on a touch device', fakeAsync(() => {
       dispatchFakeEvent(input, 'focus');
       fixture.detectChanges();
@@ -2631,6 +2645,8 @@ const SIMPLE_AUTOCOMPLETE_TEMPLATE = `
       <span>{{ state.code }}: {{ state.name }}</span>
     </mat-option>
   </mat-autocomplete>
+
+  <button class="stop-propagation" (click)="$event.stopPropagation()">Click me</button>
 `;
 
 @Component({template: SIMPLE_AUTOCOMPLETE_TEMPLATE})