Updated to minSdkVersion 20 because of Native View.

android/build.gradle

@@ -34,7 +34,8 @@ android {
         main.java.srcDirs += 'src/main/kotlin'
     }
     defaultConfig {
-        minSdkVersion 19
+        // minSdkVersion is determined by Native View.
+        minSdkVersion 20
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
     lintOptions {

example/android/app/build.gradle

@@ -38,7 +38,8 @@ android {
 
     defaultConfig {
         applicationId "net.touchcapture.qr.flutterqrexample"
-        minSdkVersion 19
+        // minSdkVersion is determined by Native View.
+        minSdkVersion 20
         targetSdkVersion 30
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName

example/android/app/src/main/res/values/styles.xml

@@ -1,10 +1,17 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
+    <!-- Theme applied to the Android Window while the process is starting -->
     <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
         <!-- Show a splash screen on the activity. Automatically removed when
              Flutter draws its first frame -->
         <item name="android:windowBackground">@drawable/launch_background</item>
     </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+     This theme determines the color of the Android Window while your
+     Flutter UI initializes, as well as behind your Flutter UI while its
+     running.
+
+     This Theme is only used starting with V2 of Flutter's Android embedding. -->
     <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
         <item name="android:windowBackground">@drawable/launch_background</item>
     </style>