Add missing window flags for styling system bars

shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java

@@ -363,13 +363,28 @@ private void restoreSystemChromeSystemUIOverlays() {
     updateSystemUiOverlays();
   }
 
+  @SuppressWarnings("deprecation")
   private void setSystemChromeSystemUIOverlayStyle(
       PlatformChannel.SystemChromeStyle systemChromeStyle) {
     Window window = activity.getWindow();
     View view = window.getDecorView();
     WindowInsetsControllerCompat windowInsetsControllerCompat =
         new WindowInsetsControllerCompat(window, view);
 
+    if (Build.VERSION.SDK_INT < 30) {
+      // Flag set to specify that this window is responsible for drawing the background for the
+      // system bars. Must be set for all operations on API < 30 excluding enforcing system
+      // bar contrasts. Deprecated in API 30.
+      window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
+
+      // Flag set to dismiss any requests for translucent system bars to be provided in lieu of what
+      // is specified by systemChromeStyle. Must be set for all operations on API < 30 operations
+      // excluding enforcing system bar contrasts. Deprecated in API 30.
+      window.clearFlags(
+          WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS
+              | WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
+    }
+
     // SYSTEM STATUS BAR -------------------------------------------------------------------
     // You can't change the color of the system status bar until SDK 21, and you can't change the
     // color of the status icons until SDK 23. We only allow both starting at 23 to ensure buttons
@@ -433,8 +448,6 @@ private void setSystemChromeSystemUIOverlayStyle(
     }
     // You can't change the color of the navigation bar divider color until SDK 28.
     if (systemChromeStyle.systemNavigationBarDividerColor != null && Build.VERSION.SDK_INT >= 28) {
-      window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
-      window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
       window.setNavigationBarDividerColor(systemChromeStyle.systemNavigationBarDividerColor);
     }
 

shell/platform/android/test/io/flutter/plugin/platform/PlatformPluginTest.java

@@ -23,6 +23,7 @@
 import android.view.View;
 import android.view.Window;
 import android.view.WindowInsetsController;
+import android.view.WindowManager;
 import androidx.activity.OnBackPressedCallback;
 import androidx.fragment.app.FragmentActivity;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
@@ -387,6 +388,29 @@ public void doNotEnableEdgeToEdgeOnOlderSdk() {
                 | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
   }
 
+  @Config(sdk = 29)
+  @Test
+  public void verifyWindowFlagsSetToStyleOverlays() {
+    View fakeDecorView = mock(View.class);
+    Window fakeWindow = mock(Window.class);
+    when(fakeWindow.getDecorView()).thenReturn(fakeDecorView);
+    Activity fakeActivity = mock(Activity.class);
+    when(fakeActivity.getWindow()).thenReturn(fakeWindow);
+    PlatformChannel fakePlatformChannel = mock(PlatformChannel.class);
+    PlatformPlugin platformPlugin = new PlatformPlugin(fakeActivity, fakePlatformChannel);
+
+    SystemChromeStyle style =
+        new SystemChromeStyle(
+            0XFF000000, Brightness.LIGHT, true, 0XFFC70039, Brightness.LIGHT, 0XFF006DB3, true);
+
+    platformPlugin.mPlatformMessageHandler.setSystemUiOverlayStyle(style);
+    verify(fakeWindow).addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
+    verify(fakeWindow)
+        .clearFlags(
+            WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS
+                | WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION);
+  }
+
   @Test
   public void popSystemNavigatorFlutterActivity() {
     Activity mockActivity = mock(Activity.class);