Add a new flag for desktop mode proto 2

Add a new system property flag to enable desktop windowing prototype 2
behavior.

Bug: 260271148
Test: mp sysuig
Change-Id: I6b5d34bb5e77980e2f1fda7abb6073b7426ea19b
diff --git a/packages/SystemUI/src/com/android/systemui/flags/Flags.kt b/packages/SystemUI/src/com/android/systemui/flags/Flags.kt
index 7558b41..dd5c81d 100644
--- a/packages/SystemUI/src/com/android/systemui/flags/Flags.kt
+++ b/packages/SystemUI/src/com/android/systemui/flags/Flags.kt
@@ -352,6 +352,12 @@
     // TODO(b/256873975): Tracking Bug
     @JvmField @Keep val WM_BUBBLE_BAR = unreleasedFlag(1111, "wm_bubble_bar")
 
+    // TODO(b/260271148): Tracking bug
+    @Keep
+    @JvmField
+    val WM_DESKTOP_WINDOWING_2 =
+        sysPropBooleanFlag(1112, "persist.wm.debug.desktop_mode_2", default = false)
+
     // 1200 - predictive back
     @Keep
     @JvmField