Configured gradle and manifest.

src/android/app/build.gradle

@@ -58,4 +58,5 @@ dependencies {
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'com.android.support.test:runner:1.0.2'
     androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
+	implementation "com.facebook.react:react-native:+" // From node_modules
 }

src/android/app/src/debug/AndroidManifest.xml

@@ -1,7 +1,14 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:tools="http://schemas.android.com/tools"
     package="com.example.rnflutter">
     <!-- Flutter needs it to communicate with the running application
          to allow setting breakpoints, to provide hot reload, etc.
     -->
     <uses-permission android:name="android.permission.INTERNET"/>
+
+	<application
+  		android:usesCleartextTraffic="true"
+		tools:targetApi="28" >
+		<activity android:name="com.facebook.react.devsupport.DevSettingsActivity" />
+	</application>
 </manifest>

src/android/app/src/main/AndroidManifest.xml

@@ -6,6 +6,9 @@
          In most cases you can leave this as-is, but you if you want to provide
          additional functionality it is fine to subclass or reimplement
          FlutterApplication and put your custom class here. -->
+
+	<uses-permission android:name="android.permission.INTERNET" />
+
     <application
         android:name="io.flutter.app.FlutterApplication"
         android:label="rnflutter"

src/android/build.gradle

@@ -13,6 +13,11 @@ allprojects {
     repositories {
         google()
         jcenter()
+
+		maven {
+            // All of React Native (JS, Android binaries) is installed from npm
+            url "$rootDir/../node_modules/react-native/android"
+        }
     }
 }
 

src/android/gradle.properties

@@ -1 +1,3 @@
 org.gradle.jvmargs=-Xmx1536M
+android.useAndroidX=true
+android.enableJetifier=true