Reland: Migrate examples to Android embedding v2 (#44139)

dev/benchmarks/macrobenchmarks/android/app/src/main/AndroidManifest.xml

@@ -23,17 +23,15 @@
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
             android:hardwareAccelerated="true"
             android:windowSoftInputMode="adjustResize">
-            <!-- This keeps the window background of the activity showing
-                 until Flutter renders its first frame. It can be removed if
-                 there is no splash screen (such as the default splash screen
-                 defined in @style/LaunchTheme). -->
-            <meta-data
-                android:name="io.flutter.app.android.SplashScreenUntilFirstFrame"
-                android:value="true" />
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>
+    <!-- Don't delete the meta-data below.
+         This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
+        <meta-data
+            android:name="flutterEmbedding"
+            android:value="2" />
     </application>
 </manifest>

dev/benchmarks/macrobenchmarks/android/app/src/main/java/com/example/macrobenchmarks/MainActivity.java

@@ -1,13 +1,13 @@
 package com.example.macrobenchmarks;
 
-import android.os.Bundle;
-import io.flutter.app.FlutterActivity;
+import androidx.annotation.NonNull;
+import io.flutter.embedding.android.FlutterActivity;
+import io.flutter.embedding.engine.FlutterEngine;
 import io.flutter.plugins.GeneratedPluginRegistrant;
 
 public class MainActivity extends FlutterActivity {
   @Override
-  protected void onCreate(Bundle savedInstanceState) {
-    super.onCreate(savedInstanceState);
-    GeneratedPluginRegistrant.registerWith(this);
+  public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
+    GeneratedPluginRegistrant.registerWith(flutterEngine);
   }
 }