fix(material/checkbox): model value not updated when using toggle method (#11902)

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

(cherry picked from commit 9371606)

Author: crisbeto

src/material/checkbox/checkbox.spec.ts

@@ -950,7 +950,7 @@ describe('MatCheckbox', () => {
     let inputElement: HTMLInputElement;
     let ngModel: NgModel;
 
-    beforeEach(() => {
+    beforeEach(fakeAsync(() => {
       fixture = createComponent(CheckboxWithNgModel);
 
       fixture.componentInstance.isRequired = false;
@@ -961,7 +961,7 @@ describe('MatCheckbox', () => {
       checkboxInstance = checkboxDebugElement.componentInstance;
       inputElement = <HTMLInputElement>checkboxNativeElement.querySelector('input');
       ngModel = checkboxDebugElement.injector.get<NgModel>(NgModel);
-    });
+    }));
 
     it('should be pristine, untouched, and valid initially', () => {
       expect(ngModel.valid).toBe(true);
@@ -1059,6 +1059,17 @@ describe('MatCheckbox', () => {
       expect(checkboxInstance.checked).toBe(false);
       expect(ngModel.valid).toBe(false);
     });
+
+    it('should update 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 name attribute', () => {

src/material/checkbox/checkbox.ts

@@ -406,6 +406,7 @@ export class MatCheckbox
   /** Toggles the `checked` state of the checkbox. */
   toggle(): void {
     this.checked = !this.checked;
+    this._controlValueAccessorChangeFn(this.checked);
   }
 
   /**
@@ -437,7 +438,7 @@ export class MatCheckbox
         });
       }
 
-      this.toggle();
+      this._checked = !this._checked;
       this._transitionCheckState(
         this._checked ? TransitionCheckState.Checked : TransitionCheckState.Unchecked,
       );