Update Actions.invoke to return the result of invoking the action. (#62012)

The boolean value as to whether the action was found and enabled
is less useful than just returning the result of invoking the action
itself.

packages/flutter/lib/src/widgets/actions.dart

@@ -581,7 +581,13 @@ class Actions extends StatefulWidget {
   /// that are found.
   ///
   /// Setting `nullOk` to true means that if no ambient [Actions] widget is
-  /// found, then this method will return false instead of throwing.
+  /// found, then this method will return null instead of throwing.
+  ///
+  /// Returns the result of invoking the action's [Action.invoke] method. If
+  /// no action mapping was found for the specified intent, or if the action
+  /// that was found was disabled, then this returns null. Callers can detect
+  /// whether or not the action is available (found, and not disabled) using
+  /// [Actions.find] with its `nullOk` argument set to true.
   static Object invoke<T extends Intent>(
     BuildContext context,
     T intent, {
@@ -624,7 +630,7 @@ class Actions extends StatefulWidget {
     }());
     // Invoke the action we found using the relevant dispatcher from the Actions
     // Element we found.
-    return actionElement != null ? _findDispatcher(actionElement).invokeAction(action, intent, context) != null : null;
+    return actionElement != null ? _findDispatcher(actionElement).invokeAction(action, intent, context) : null;
   }
 
   @override

packages/flutter/test/widgets/actions_test.dart

@@ -423,6 +423,36 @@ void main() {
 
       expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.forbidden);
     });
+    testWidgets('Actions.invoke returns the value of Action.invoke', (WidgetTester tester) async {
+      final GlobalKey containerKey = GlobalKey();
+      final Object sentinel = Object();
+      bool invoked = false;
+      const TestIntent intent = TestIntent();
+      final Action<Intent> testAction = TestAction(
+        onInvoke: (Intent intent) {
+          invoked = true;
+          return sentinel;
+        },
+      );
+
+      await tester.pumpWidget(
+        Actions(
+          dispatcher: TestDispatcher(postInvoke: collect),
+          actions: <Type, Action<Intent>>{
+            TestIntent: testAction,
+          },
+          child: Container(key: containerKey),
+        ),
+      );
+
+      await tester.pump();
+      final Object result = Actions.invoke<TestIntent>(
+        containerKey.currentContext,
+        intent,
+      );
+      expect(identical(result, sentinel), isTrue);
+      expect(invoked, isTrue);
+    });
   });
 
   group('Listening', () {
@@ -484,7 +514,7 @@ void main() {
         const TestIntent(),
       );
       expect(enabled1, isFalse);
-      expect(result, isFalse);
+      expect(result, isNull);
       expect(invoked1, isFalse);
 
       action1.enabled = true;
@@ -523,7 +553,7 @@ void main() {
       );
       expect(enabledChanged, isNull);
       expect(enabled2, isFalse);
-      expect(result, isFalse);
+      expect(result, isNull);
       expect(invoked2, isFalse);
 
       action2.enabled = true;