fix(input): AutofillMonitor stream not being completed when stopping monitoring (#9886)

Currently we only remove the event listeners and CSS classes when we stop monitoring an element, however any subscriptions are still live. These changes complete the subject since it won't be reused if we decide to start monitoring again.

src/lib/input/autofill.spec.ts

@@ -137,6 +137,19 @@ describe('AutofillMonitor', () => {
     autofillMonitor.stopMonitoring(inputEl);
     expect(inputEl.classlist).not.toContain('mat-input-autofilled');
   });
+
+  it('should complete the stream when monitoring is stopped', () => {
+    const element = testComponent.input1.nativeElement;
+    const autofillStream = autofillMonitor.monitor(element);
+    const spy = jasmine.createSpy('autofillStream complete');
+
+    autofillStream.subscribe(undefined, undefined, spy);
+    expect(spy).not.toHaveBeenCalled();
+
+    autofillMonitor.stopMonitoring(element);
+    expect(spy).toHaveBeenCalled();
+  });
+
 });
 
 describe('matAutofill', () => {

src/lib/input/autofill.ts

@@ -97,8 +97,10 @@ export class AutofillMonitor implements OnDestroy {
    */
   stopMonitoring(element: Element) {
     const info = this._monitoredElements.get(element);
+
     if (info) {
       info.unlisten();
+      info.subject.complete();
       element.classList.remove('mat-input-autofill-monitored');
       element.classList.remove('mat-input-autofilled');
       this._monitoredElements.delete(element);
@@ -106,10 +108,7 @@ export class AutofillMonitor implements OnDestroy {
   }
 
   ngOnDestroy() {
-    this._monitoredElements.forEach(info => {
-      info.unlisten();
-      info.subject.complete();
-    });
+    this._monitoredElements.forEach((_info, element) => this.stopMonitoring(element));
   }
 }
 
@@ -119,13 +118,14 @@ export class AutofillMonitor implements OnDestroy {
   selector: '[matAutofill]',
 })
 export class MatAutofill implements OnDestroy, OnInit {
-  @Output() matAutofill = new EventEmitter<AutofillEvent>();
+  @Output() matAutofill: EventEmitter<AutofillEvent> = new EventEmitter<AutofillEvent>();
 
   constructor(private _elementRef: ElementRef, private _autofillMonitor: AutofillMonitor) {}
 
   ngOnInit() {
-    this._autofillMonitor.monitor(this._elementRef.nativeElement)
-        .subscribe(event => this.matAutofill.emit(event));
+    this._autofillMonitor
+      .monitor(this._elementRef.nativeElement)
+      .subscribe(event => this.matAutofill.emit(event));
   }
 
   ngOnDestroy() {