Allow serving Custom ads in AdLoaderAd

Allow the `AdLoaderAd` instance to serve `Custom` ads, which are
instances of:

  * `NativeCustomFormatAd` under Android, and
  * `GADCustomNativeAd` under iOS

packages/google_mobile_ads/android/src/main/java/io/flutter/plugins/googlemobileads/AdMessageCodec.java

@@ -67,6 +67,7 @@ class AdMessageCodec extends StandardMessageCodec {
   private static final byte VALUE_COLOR = (byte) 153;
   private static final byte VALUE_AD_MANAGER_AD_VIEW_OPTIONS = (byte) 154;
   private static final byte VALUE_BANNER_PARAMETERS = (byte) 155;
+  private static final byte VALUE_CUSTOM_PARAMETERS = (byte) 156;
 
   @NonNull Context context;
   @NonNull final FlutterAdSize.AdSizeFactory adSizeFactory;
@@ -253,6 +254,11 @@ protected void writeValue(ByteArrayOutputStream stream, Object value) {
       FlutterBannerParameters bannerParameters = (FlutterBannerParameters) value;
       writeValue(stream, bannerParameters.sizes);
       writeValue(stream, bannerParameters.adManagerAdViewOptions);
+    } else if (value instanceof FlutterCustomParameters) {
+      stream.write(VALUE_CUSTOM_PARAMETERS);
+      FlutterCustomParameters customParameters = (FlutterCustomParameters) value;
+      writeValue(stream, customParameters.formatIds);
+      writeValue(stream, customParameters.viewOptions);
     } else {
       super.writeValue(stream, value);
     }
@@ -419,6 +425,10 @@ protected Object readValueOfType(byte type, ByteBuffer buffer) {
         return new FlutterBannerParameters(
             (List<FlutterAdSize>) readValueOfType(buffer.get(), buffer),
             (FlutterAdManagerAdViewOptions) readValueOfType(buffer.get(), buffer));
+      case VALUE_CUSTOM_PARAMETERS:
+        return new FlutterCustomParameters(
+            (List<String>) readValueOfType(buffer.get(), buffer),
+            (Map<String, Object>) readValueOfType(buffer.get(), buffer));
       default:
         return super.readValueOfType(type, buffer);
     }

packages/google_mobile_ads/android/src/main/java/io/flutter/plugins/googlemobileads/FlutterAdListener.java

@@ -20,6 +20,8 @@
 import com.google.android.gms.ads.formats.OnAdManagerAdViewLoadedListener;
 import com.google.android.gms.ads.nativead.NativeAd;
 import com.google.android.gms.ads.nativead.NativeAd.OnNativeAdLoadedListener;
+import com.google.android.gms.ads.nativead.NativeCustomFormatAd;
+import com.google.android.gms.ads.nativead.NativeCustomFormatAd.OnCustomFormatAdLoadedListener;
 import java.lang.ref.WeakReference;
 
 /** Callback type to notify when an ad successfully loads. */
@@ -137,3 +139,20 @@ public void onAdManagerAdViewLoaded(AdManagerAdView adView) {
     }
   }
 }
+
+/** {@link OnCustomFormatAdLoadedListener} for custom ads. */
+class FlutterCustomFormatAdLoadedListener implements OnCustomFormatAdLoadedListener {
+
+  private final WeakReference<OnCustomFormatAdLoadedListener> reference;
+
+  FlutterCustomFormatAdLoadedListener(OnCustomFormatAdLoadedListener listener) {
+    reference = new WeakReference<>(listener);
+  }
+
+  @Override
+  public void onCustomFormatAdLoaded(NativeCustomFormatAd ad) {
+    if (reference.get() != null) {
+      reference.get().onCustomFormatAdLoaded(ad);
+    }
+  }
+}

packages/google_mobile_ads/android/src/main/java/io/flutter/plugins/googlemobileads/FlutterAdLoader.java

@@ -146,14 +146,20 @@ public void loadAdLoaderAd(
       @NonNull String adUnitId,
       @NonNull AdListener adListener,
       @NonNull AdRequest request,
-      @Nullable FlutterAdLoaderAd.BannerParameters bannerParameters) {
+      @Nullable FlutterAdLoaderAd.BannerParameters bannerParameters,
+      @Nullable FlutterAdLoaderAd.CustomParameters customParameters) {
     AdLoader.Builder builder = new AdLoader.Builder(context, adUnitId);
     if (bannerParameters != null) {
       builder = builder.forAdManagerAdView(bannerParameters.listener, bannerParameters.adSizes);
       if (bannerParameters.adManagerAdViewOptions != null) {
         builder.withAdManagerAdViewOptions(bannerParameters.adManagerAdViewOptions);
       }
     }
+    if (customParameters != null) {
+      for (String formatId : customParameters.factories.keySet()) {
+        builder = builder.forCustomFormatAd(formatId, customParameters.listener, null);
+      }
+    }
     builder.withAdListener(adListener).build().loadAd(request);
   }
 
@@ -162,14 +168,20 @@ public void loadAdManagerAdLoaderAd(
       @NonNull String adUnitId,
       @NonNull AdListener adListener,
       @NonNull AdManagerAdRequest adManagerAdRequest,
-      @Nullable FlutterAdLoaderAd.BannerParameters bannerParameters) {
+      @Nullable FlutterAdLoaderAd.BannerParameters bannerParameters,
+      @Nullable FlutterAdLoaderAd.CustomParameters customParameters) {
     AdLoader.Builder builder = new AdLoader.Builder(context, adUnitId);
     if (bannerParameters != null) {
       builder = builder.forAdManagerAdView(bannerParameters.listener, bannerParameters.adSizes);
       if (bannerParameters.adManagerAdViewOptions != null) {
         builder.withAdManagerAdViewOptions(bannerParameters.adManagerAdViewOptions);
       }
     }
+    if (customParameters != null) {
+      for (String formatId : customParameters.factories.keySet()) {
+        builder = builder.forCustomFormatAd(formatId, customParameters.listener, null);
+      }
+    }
     builder.withAdListener(adListener).build().loadAd(adManagerAdRequest);
   }
 }

packages/google_mobile_ads/android/src/main/java/io/flutter/plugins/googlemobileads/FlutterAdLoaderAd.java

@@ -24,13 +24,18 @@
 import com.google.android.gms.ads.admanager.AdManagerAdView;
 import com.google.android.gms.ads.formats.AdManagerAdViewOptions;
 import com.google.android.gms.ads.formats.OnAdManagerAdViewLoadedListener;
+import com.google.android.gms.ads.nativead.NativeCustomFormatAd;
+import com.google.android.gms.ads.nativead.NativeCustomFormatAd.OnCustomFormatAdLoadedListener;
 import io.flutter.plugin.platform.PlatformView;
+import io.flutter.plugins.googlemobileads.GoogleMobileAdsPlugin.CustomAdFactory;
+import java.util.Map;
 
 /**
  * A central wrapper for {@link AdManagerAdView}, {@link NativeCustomFormatAd} and {@link NativeAd}
  * instances served for a single {@link AdRequest} or {@link AdManagerAdRequest}
  */
-class FlutterAdLoaderAd extends FlutterAd implements OnAdManagerAdViewLoadedListener {
+class FlutterAdLoaderAd extends FlutterAd
+    implements OnAdManagerAdViewLoadedListener, OnCustomFormatAdLoadedListener {
   private static final String TAG = "FlutterAdLoaderAd";
 
   @NonNull private final AdInstanceManager manager;
@@ -40,6 +45,7 @@ class FlutterAdLoaderAd extends FlutterAd implements OnAdManagerAdViewLoadedList
   @Nullable private FlutterAdManagerAdRequest adManagerRequest;
   @Nullable private View view;
   @Nullable protected BannerParameters bannerParameters;
+  @Nullable protected CustomParameters customParameters;
 
   static class Builder {
     @Nullable private AdInstanceManager manager;
@@ -49,6 +55,8 @@ static class Builder {
     @Nullable private Integer id;
     @Nullable private FlutterAdLoader adLoader;
     @Nullable private FlutterBannerParameters bannerParameters;
+    @Nullable private FlutterCustomParameters customParameters;
+    @Nullable private Map<String, CustomAdFactory> customFactories;
 
     public Builder setId(int id) {
       this.id = id;
@@ -85,6 +93,17 @@ public Builder setBanner(@Nullable FlutterBannerParameters bannerParameters) {
       return this;
     }
 
+    public Builder setCustom(@Nullable FlutterCustomParameters customParameters) {
+      this.customParameters = customParameters;
+      return this;
+    }
+
+    public Builder withAvailableCustomFactories(
+        @NonNull Map<String, CustomAdFactory> customFactories) {
+      this.customFactories = customFactories;
+      return this;
+    }
+
     FlutterAdLoaderAd build() {
       if (manager == null) {
         throw new IllegalStateException("manager must be provided");
@@ -112,6 +131,12 @@ FlutterAdLoaderAd build() {
                 new FlutterAdManagerAdViewLoadedListener(adLoaderAd));
       }
 
+      if (customParameters != null) {
+        adLoaderAd.customParameters =
+            customParameters.asCustomParameters(
+                new FlutterCustomFormatAdLoadedListener(adLoaderAd), customFactories);
+      }
+
       return adLoaderAd;
     }
   }
@@ -131,6 +156,21 @@ static class BannerParameters {
     }
   }
 
+  static class CustomParameters {
+    @NonNull final OnCustomFormatAdLoadedListener listener;
+    @NonNull final Map<String, CustomAdFactory> factories;
+    @Nullable final Map<String, Object> viewOptions;
+
+    CustomParameters(
+        @NonNull OnCustomFormatAdLoadedListener listener,
+        @NonNull Map<String, CustomAdFactory> factories,
+        @Nullable Map<String, Object> viewOptions) {
+      this.listener = listener;
+      this.factories = factories;
+      this.viewOptions = viewOptions;
+    }
+  }
+
   protected FlutterAdLoaderAd(
       int adId,
       @NonNull AdInstanceManager manager,
@@ -164,13 +204,17 @@ void load() {
     // As of 20.0.0 of GMA, mockito is unable to mock AdLoader.
     if (request != null) {
       adLoader.loadAdLoaderAd(
-          adUnitId, adListener, request.asAdRequest(adUnitId), bannerParameters);
+          adUnitId, adListener, request.asAdRequest(adUnitId), bannerParameters, customParameters);
       return;
     }
 
     if (adManagerRequest != null) {
       adLoader.loadAdManagerAdLoaderAd(
-          adUnitId, adListener, adManagerRequest.asAdManagerAdRequest(adUnitId), bannerParameters);
+          adUnitId,
+          adListener,
+          adManagerRequest.asAdManagerAdRequest(adUnitId),
+          bannerParameters,
+          customParameters);
       return;
     }
 
@@ -193,6 +237,14 @@ public void onAdManagerAdViewLoaded(@NonNull AdManagerAdView adView) {
     manager.onAdLoaded(adId, adView.getResponseInfo());
   }
 
+  @Override
+  public void onCustomFormatAdLoaded(@NonNull NativeCustomFormatAd ad) {
+    String formatId = ad.getCustomFormatId();
+    view =
+        customParameters.factories.get(formatId).createCustomAd(ad, customParameters.viewOptions);
+    manager.onAdLoaded(adId, null);
+  }
+
   @Override
   void dispose() {
     if (view == null) {

packages/google_mobile_ads/android/src/main/java/io/flutter/plugins/googlemobileads/FlutterCustomParameters.java

@@ -0,0 +1,30 @@
+package io.flutter.plugins.googlemobileads;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import com.google.android.gms.ads.nativead.NativeCustomFormatAd.OnCustomFormatAdLoadedListener;
+import io.flutter.plugins.googlemobileads.GoogleMobileAdsPlugin.CustomAdFactory;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+class FlutterCustomParameters {
+  @NonNull final List<String> formatIds;
+  @Nullable final Map<String, Object> viewOptions;
+
+  FlutterCustomParameters(
+      @NonNull List<String> formatIds, @Nullable Map<String, Object> viewOptions) {
+    this.formatIds = formatIds;
+    this.viewOptions = viewOptions;
+  }
+
+  FlutterAdLoaderAd.CustomParameters asCustomParameters(
+      @NonNull OnCustomFormatAdLoadedListener listener,
+      @NonNull Map<String, CustomAdFactory> availableFactories) {
+    Map<String, CustomAdFactory> factories = new HashMap<>();
+    for (String formatId : formatIds) {
+      factories.put(formatId, availableFactories.get(formatId));
+    }
+    return new FlutterAdLoaderAd.CustomParameters(listener, factories, viewOptions);
+  }
+}