Do not update system UI overlays when the SDK version condition is not met (flutter#29643)

Author: wytesk133

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

@@ -238,11 +238,7 @@ public void onSystemUiVisibilityChange(int visibility) {
   }
 
   private void setSystemChromeEnabledSystemUIMode(PlatformChannel.SystemUiMode systemUiMode) {
-    int enabledOverlays =
-        DEFAULT_SYSTEM_UI
-            | View.SYSTEM_UI_FLAG_FULLSCREEN
-            | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
-            | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
+    int enabledOverlays;
 
     if (systemUiMode == PlatformChannel.SystemUiMode.LEAN_BACK
         && Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
@@ -301,6 +297,9 @@ private void setSystemChromeEnabledSystemUIMode(PlatformChannel.SystemUiMode sys
           View.SYSTEM_UI_FLAG_LAYOUT_STABLE
               | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
               | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN;
+    } else {
+      // When none of the conditions are matched, return without updating the system UI overlays.
+      return;
     }
 
     mEnabledOverlays = enabledOverlays;

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

@@ -367,6 +367,26 @@ public void setSystemUiMode() {
     }
   }
 
+  @Config(sdk = 28)
+  @Test
+  public void doNotEnableEdgeToEdgeOnOlderSdk() {
+    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);
+
+    platformPlugin.mPlatformMessageHandler.showSystemUiMode(
+        PlatformChannel.SystemUiMode.EDGE_TO_EDGE);
+    verify(fakeDecorView, never())
+        .setSystemUiVisibility(
+            View.SYSTEM_UI_FLAG_LAYOUT_STABLE
+                | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
+                | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
+  }
+
   @Test
   public void popSystemNavigatorFlutterActivity() {
     Activity mockActivity = mock(Activity.class);