fix(checkbox): model value not updated when using toggle method

Along the same lines as #11812. The checkbox doesn't update its `ControlValueAccessor` value when it is toggled via the `toggle` method.

src/lib/checkbox/checkbox.spec.ts

@@ -877,15 +877,15 @@ describe('MatCheckbox', () => {
     let checkboxInstance: MatCheckbox;
     let inputElement: HTMLInputElement;
 
-    beforeEach(() => {
+    beforeEach(fakeAsync(() => {
       fixture = TestBed.createComponent(CheckboxWithFormDirectives);
       fixture.detectChanges();
 
       checkboxDebugElement = fixture.debugElement.query(By.directive(MatCheckbox));
       checkboxNativeElement = checkboxDebugElement.nativeElement;
       checkboxInstance = checkboxDebugElement.componentInstance;
       inputElement = <HTMLInputElement>checkboxNativeElement.querySelector('input');
-    });
+    }));
 
     it('should be in pristine, untouched, and valid states initially', fakeAsync(() => {
       flush();
@@ -914,6 +914,17 @@ describe('MatCheckbox', () => {
 
       expect(checkboxInstance.checked).toBe(false);
     });
+
+    it('should updated the ngModel value when using the `toggle` method', fakeAsync(() => {
+      const checkbox = fixture.debugElement.query(By.directive(MatCheckbox)).componentInstance;
+
+      expect(fixture.componentInstance.isGood).toBe(false);
+
+      checkbox.toggle();
+      fixture.detectChanges();
+
+      expect(fixture.componentInstance.isGood).toBe(true);
+    }));
   });
 
   describe('with required ngModel', () => {

src/lib/checkbox/checkbox.ts

@@ -337,6 +337,7 @@ export class MatCheckbox extends _MatCheckboxMixinBase implements ControlValueAc
   /** Toggles the `checked` state of the checkbox. */
   toggle(): void {
     this.checked = !this.checked;
+    this._controlValueAccessorChangeFn(this.checked);
   }
 
   /**