[FP5-2896] [Desktop moke]The application interface in the recent interface is blank after disconnect the second screen

* Root Cause
  disconnet desktop Task snapshot is null
* Solution
  refresh task when desktop is on
* Test Steps
  test Desktop
* Test Result
  pass

Change-Id: I87a5d1e90c3080ae114a63b4a813263243a44e25
diff --git a/quickstep/src/com/android/quickstep/RecentTasksList.java b/quickstep/src/com/android/quickstep/RecentTasksList.java
index 6b616b1..608d580 100644
--- a/quickstep/src/com/android/quickstep/RecentTasksList.java
+++ b/quickstep/src/com/android/quickstep/RecentTasksList.java
@@ -125,6 +125,9 @@
      */
     public synchronized int getTasks(boolean loadKeysOnly,
             Consumer<ArrayList<GroupTask>> callback) {
+        if(mSysUiProxy.isDesktopOn()) {
+            invalidateLoadedTasks();
+        }
         final int requestLoadId = mChangeId;
         if (mResultsUi.isValidForRequest(requestLoadId, loadKeysOnly)) {
             // The list is up to date, send the callback on the next frame,
diff --git a/quickstep/src/com/android/quickstep/SystemUiProxy.java b/quickstep/src/com/android/quickstep/SystemUiProxy.java
index 3b2df31..159217e 100644
--- a/quickstep/src/com/android/quickstep/SystemUiProxy.java
+++ b/quickstep/src/com/android/quickstep/SystemUiProxy.java
@@ -19,6 +19,7 @@
 
 import static com.android.launcher3.util.Executors.MAIN_EXECUTOR;
 import static com.android.launcher3.util.Executors.UI_HELPER_EXECUTOR;
+import static android.provider.Settings.Global.DEVELOPMENT_FORCE_DESKTOP_MODE_ON_EXTERNAL_DISPLAYS;
 
 import android.app.ActivityManager;
 import android.app.PendingIntent;
@@ -44,6 +45,7 @@
 import android.view.RemoteAnimationTarget;
 import android.view.SurfaceControl;
 import android.window.IOnBackInvokedCallback;
+import android.provider.Settings;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.WorkerThread;
@@ -926,4 +928,10 @@
             }
         }
     }
+
+    public boolean isDesktopOn(){
+        boolean desktopOn = Settings.Global.getInt(mContext.getContentResolver(),
+                DEVELOPMENT_FORCE_DESKTOP_MODE_ON_EXTERNAL_DISPLAYS, 0) == 1;
+        return desktopOn;
+    }
 }