packages/google_sign_in/google_sign_in/example/android/app/src/main/AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="io.flutter.plugins.googlesigninexample">

    <uses-permission android:name="android.permission.INTERNET"/>

    <application>
        <activity android:name="io.flutter.embedding.android.FlutterActivity"
                  android:theme="@android:style/Theme.Black.NoTitleBar"
                  android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection"
                  android:hardwareAccelerated="true"
                  android:windowSoftInputMode="adjustResize">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <meta-data android:name="flutterEmbedding" android:value="2"/>
    </application>
</manifest>