Change ModalComponent to use OnPush

PiperOrigin-RevId: 242779022

Author: TedSander

angular_components/lib/laminate/components/modal/modal.dart

@@ -154,6 +154,7 @@ abstract class Modal {
       <ng-content></ng-content>
     </template>
   ''',
+  changeDetection: ChangeDetectionStrategy.OnPush,
   // TODO(google): Change preserveWhitespace to false to improve codesize.
   preserveWhitespace: true,
   visibility: Visibility.all, // Injected by dialog, et al.
@@ -182,7 +183,7 @@ class ModalComponent
   bool _isDestroyed = false;
   bool _isHidden = false;
   bool _isVisible = false;
-  OverlayRef _resolvedOverlayRef;
+  final OverlayRef _resolvedOverlayRef;
   Element _lastFocusedElement;
 
   /// Whether to return focus to the last focused element before the modal
@@ -196,9 +197,13 @@ class ModalComponent
   Future<bool> _pendingClose;
 
   ModalComponent(OverlayService overlayService, this._element, this._domService,
-      @Optional() @SkipSelf() this._parentModal, @Optional() this._stack) {
-    _createdOverlayRef(
-        overlayService.createOverlayRefSync(OverlayState.Dialog));
+      @Optional() @SkipSelf() this._parentModal, @Optional() this._stack)
+      : _resolvedOverlayRef =
+            overlayService.createOverlayRefSync(OverlayState.Dialog) {
+    _disposer
+      ..addDisposable(_resolvedOverlayRef)
+      ..addStreamSubscription(_resolvedOverlayRef.onVisibleChanged
+          .listen(_onOverlayVisibleChanged));
   }
 
   @Input()
@@ -223,20 +228,6 @@ class ModalComponent
     _disposer.dispose();
   }
 
-  void _createdOverlayRef(OverlayRef overlayRef) {
-    // If the modal is closed before the overlay is created we should dispose
-    // the ref to avoid leaks since `onDestroy` was already called.
-    if (_isDestroyed) {
-      overlayRef.dispose();
-    } else {
-      _resolvedOverlayRef = overlayRef;
-      _disposer
-        ..addDisposable(_resolvedOverlayRef)
-        ..addStreamSubscription(_resolvedOverlayRef.onVisibleChanged
-            .listen(_onOverlayVisibleChanged));
-    }
-  }
-
   // A callback received when the overlay reports a visibility change.
   void _onOverlayVisibleChanged(bool isVisible) {
     _isVisible = isVisible;