Swtich to screenshot before trigger the desk launch

Bug: 400870600
Test: m
Flag: com.android.window.flags.enable_multiple_desktops_frontend
Flag: com.android.window.flags.enable_multiple_desktops_backend
Change-Id: I7a622a2fa865ddb26d902e0bf13f1e69257e2dfa

quickstep/src/com/android/quickstep/views/DesktopTaskView.kt

@@ -417,8 +417,22 @@ class DesktopTaskView @JvmOverloads constructor(context: Context, attrs: Attribu
         val endCallback = RunnableList()
         val desktopController = recentsView.desktopRecentsController
         checkNotNull(desktopController) { "recentsController is null" }
-        desktopController.launchDesktopFromRecents(this, animated) {
-            endCallback.executeAllAndDestroy()
+
+        val launchDesktopFromRecents = {
+            desktopController.launchDesktopFromRecents(this, animated) {
+                endCallback.executeAllAndDestroy()
+            }
+        }
+        if (enableMultipleDesktops(context) && desktopTask?.tasks?.isEmpty() == true) {
+            recentsView.switchToScreenshot {
+                recentsView.finishRecentsAnimation(
+                    /* toRecents= */ true,
+                    /* shouldPip= */ false,
+                    launchDesktopFromRecents,
+                )
+            }
+        } else {
+            launchDesktopFromRecents()
         }
         Log.d(
             TAG,

quickstep/src/com/android/quickstep/views/RecentsViewUtils.kt

@@ -303,11 +303,6 @@ class RecentsViewUtils(private val recentsView: RecentsView<*, *>) : DesktopVisi
         }
     }
 
-    override fun onActiveDeskChanged(displayId: Int, newActiveDesk: Int, oldActiveDesk: Int) {
-        // TODO: b/400870600 - We may need to add code here to special case when an empty desk gets
-        // activated, since `RemoteDesktopLaunchTransitionRunner` doesn't always get triggered.
-    }
-
     /**
      * Gets the list of accessibility children. Currently all the children of RecentsViews are
      * added, and in the reverse order to the list.