Removed remaining use of static stack ids.

Replace by windowingMode and activityType.

Test: Existing tests pass.
Test: go/wm-smoke
Bug: 64146578
Change-Id: I2ff026de3ead1a3e7136df17c68ed37d7aae5495
diff --git a/services/core/java/com/android/server/wm/WallpaperController.java b/services/core/java/com/android/server/wm/WallpaperController.java
index 7213c95..629cc86 100644
--- a/services/core/java/com/android/server/wm/WallpaperController.java
+++ b/services/core/java/com/android/server/wm/WallpaperController.java
@@ -18,7 +18,7 @@
 
 import com.android.internal.util.ToBooleanFunction;
 
-import static android.app.ActivityManager.StackId.FREEFORM_WORKSPACE_STACK_ID;
+import static android.app.WindowConfiguration.WINDOWING_MODE_FREEFORM;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.view.WindowManager.LayoutParams.FLAG_SHOW_WALLPAPER;
 import static android.view.WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED;
@@ -447,7 +447,7 @@
 
     private void findWallpaperTarget(DisplayContent dc) {
         mFindResults.reset();
-        if (dc.isStackVisible(FREEFORM_WORKSPACE_STACK_ID)) {
+        if (dc.isStackVisible(WINDOWING_MODE_FREEFORM)) {
             // In freeform mode we set the wallpaper as its own target, so we don't need an
             // additional window to make it visible.
             mFindResults.setUseTopWallpaperAsTarget(true);