Fix intent builder visibility (#18875)

shell/platform/android/BUILD.gn

@@ -428,6 +428,7 @@ action("robolectric_tests") {
     "test/io/flutter/embedding/android/FlutterActivityAndFragmentDelegateTest.java",
     "test/io/flutter/embedding/android/FlutterActivityTest.java",
     "test/io/flutter/embedding/android/FlutterAndroidComponentTest.java",
+    "test/io/flutter/embedding/android/FlutterFragmentActivityTest.java",
     "test/io/flutter/embedding/android/FlutterFragmentTest.java",
     "test/io/flutter/embedding/android/FlutterViewTest.java",
     "test/io/flutter/embedding/android/RobolectricFlutterActivity.java",

shell/platform/android/io/flutter/embedding/android/FlutterActivity.java

@@ -241,7 +241,7 @@ public class FlutterActivity extends Activity
      *
      * <p>{@code return new NewEngineIntentBuilder(MyFlutterActivity.class); }
      */
-    protected NewEngineIntentBuilder(@NonNull Class<? extends FlutterActivity> activityClass) {
+    public NewEngineIntentBuilder(@NonNull Class<? extends FlutterActivity> activityClass) {
       this.activityClass = activityClass;
     }
 
@@ -314,12 +314,12 @@ public class FlutterActivity extends Activity
      * {@code FlutterActivity}.
      *
      * <p>Subclasses of {@code FlutterActivity} should provide their own static version of {@link
-     * #withNewEngine()}, which returns an instance of {@code CachedEngineIntentBuilder} constructed
-     * with a {@code Class} reference to the {@code FlutterActivity} subclass, e.g.:
+     * #withCachedEngine()}, which returns an instance of {@code CachedEngineIntentBuilder}
+     * constructed with a {@code Class} reference to the {@code FlutterActivity} subclass, e.g.:
      *
      * <p>{@code return new CachedEngineIntentBuilder(MyFlutterActivity.class, engineId); }
      */
-    protected CachedEngineIntentBuilder(
+    public CachedEngineIntentBuilder(
         @NonNull Class<? extends FlutterActivity> activityClass, @NonNull String engineId) {
       this.activityClass = activityClass;
       this.cachedEngineId = engineId;

shell/platform/android/io/flutter/embedding/android/FlutterFragmentActivity.java

@@ -101,8 +101,7 @@ public class FlutterFragmentActivity extends FragmentActivity
      *
      * <p>{@code return new NewEngineIntentBuilder(MyFlutterActivity.class); }
      */
-    protected NewEngineIntentBuilder(
-        @NonNull Class<? extends FlutterFragmentActivity> activityClass) {
+    public NewEngineIntentBuilder(@NonNull Class<? extends FlutterFragmentActivity> activityClass) {
       this.activityClass = activityClass;
     }
 
@@ -177,13 +176,13 @@ public class FlutterFragmentActivity extends FragmentActivity
      * {@code FlutterFragmentActivity}.
      *
      * <p>Subclasses of {@code FlutterFragmentActivity} should provide their own static version of
-     * {@link #withNewEngine()}, which returns an instance of {@code CachedEngineIntentBuilder}
+     * {@link #withCachedEngine()}, which returns an instance of {@code CachedEngineIntentBuilder}
      * constructed with a {@code Class} reference to the {@code FlutterFragmentActivity} subclass,
      * e.g.:
      *
      * <p>{@code return new CachedEngineIntentBuilder(MyFlutterActivity.class, engineId); }
      */
-    protected CachedEngineIntentBuilder(
+    public CachedEngineIntentBuilder(
         @NonNull Class<? extends FlutterFragmentActivity> activityClass, @NonNull String engineId) {
       this.activityClass = activityClass;
       this.cachedEngineId = engineId;

shell/platform/android/test/io/flutter/FlutterTestSuite.java

@@ -7,6 +7,7 @@ package io.flutter;
 import io.flutter.embedding.android.FlutterActivityAndFragmentDelegateTest;
 import io.flutter.embedding.android.FlutterActivityTest;
 import io.flutter.embedding.android.FlutterAndroidComponentTest;
+import io.flutter.embedding.android.FlutterFragmentActivityTest;
 import io.flutter.embedding.android.FlutterFragmentTest;
 import io.flutter.embedding.android.FlutterViewTest;
 import io.flutter.embedding.engine.FlutterEngineCacheTest;
@@ -42,6 +43,7 @@ import test.io.flutter.embedding.engine.dart.DartExecutorTest;
   FlutterEngineCacheTest.class,
   FlutterEnginePluginRegistryTest.class,
   FlutterEngineTest.class,
+  FlutterFragmentActivityTest.class,
   FlutterFragmentTest.class,
   FlutterJNITest.class,
   FlutterLaunchTests.class,

shell/platform/android/test/io/flutter/embedding/android/FlutterActivityTest.java

@@ -175,4 +175,16 @@ public class FlutterActivityTest {
           context, mock(FlutterLoader.class), flutterJNI, new String[] {}, false);
     }
   }
+
+  // This is just a compile time check to ensure that it's possible for FlutterActivity subclasses
+  // to provide their own intent builders which builds their own runtime types.
+  static class FlutterActivityWithIntentBuilders extends FlutterActivity {
+    public static NewEngineIntentBuilder withNewEngine() {
+      return new NewEngineIntentBuilder(FlutterActivityWithIntentBuilders.class);
+    }
+
+    public static CachedEngineIntentBuilder withCachedEngine(@NonNull String cachedEngineId) {
+      return new CachedEngineIntentBuilder(FlutterActivityWithIntentBuilders.class, cachedEngineId);
+    }
+  }
 }

shell/platform/android/test/io/flutter/embedding/android/FlutterFragmentActivityTest.java

+package io.flutter.embedding.android;
+
+import static org.junit.Assert.assertTrue;
+
+import androidx.annotation.NonNull;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+@Config(manifest = Config.NONE)
+@RunWith(RobolectricTestRunner.class)
+public class FlutterFragmentActivityTest {
+  @Test
+  public void placeholder() {
+    // This is just a placeholder since this file only has a compile check currently.
+    // Delete when adding the first real test.
+    assertTrue(true);
+  }
+
+  // This is just a compile time check to ensure that it's possible for FlutterFragmentActivity
+  // subclasses
+  // to provide their own intent builders which builds their own runtime types.
+  static class FlutterFragmentActivityWithIntentBuilders extends FlutterFragmentActivity {
+    public static NewEngineIntentBuilder withNewEngine() {
+      return new NewEngineIntentBuilder(FlutterFragmentActivityWithIntentBuilders.class);
+    }
+
+    public static CachedEngineIntentBuilder withCachedEngine(@NonNull String cachedEngineId) {
+      return new CachedEngineIntentBuilder(
+          FlutterFragmentActivityWithIntentBuilders.class, cachedEngineId);
+    }
+  }
+}