Resize mRemoteTargetHandles when RecentsAnimationStarts

* TopTaskTracker gets updated too late after we've exited
split screen so we can't use that to determine how many
RemoteTargetHandles to use
* We default to 2, and then scale it down to 1. Because we
modify the array holding the handles directly, it should
also get updated in AbsSwipeUpHandler
* Temporary solution to stop setting up RecentsView if we detect that
TopTaskTracker has incorrect data and re-setup when we get
onRecentsAnimationStart()

Test: Tested quickswitch in gestural and recents button
double tap in button nav.
Bug: 236226779
Flag: none

Change-Id: I1bae7aed1f8712ddd1bf496acfcb851c0e32a115

quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java

@@ -147,6 +147,7 @@ import com.android.wm.shell.startingsurface.SplashScreenExitAnimationUtils;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Consumer;
 
@@ -662,6 +663,14 @@ public abstract class AbsSwipeUpHandler<T extends StatefulActivity<S>,
         } else {
             runningTasks = mGestureState.getRunningTask().getPlaceholderTasks();
         }
+
+        // Safeguard against any null tasks being sent to recents view, happens when quickswitching
+        // very quickly w/ split tasks because TopTaskTracker provides stale information compared to
+        // actual running tasks in the recents animation.
+        // TODO(b/236226779), Proper fix (ag/22237143)
+        if (Arrays.stream(runningTasks).anyMatch(Objects::isNull)) {
+            return;
+        }
         mRecentsView.onGestureAnimationStart(runningTasks, mDeviceState.getRotationTouchHelper());
     }
 
@@ -915,7 +924,12 @@ public abstract class AbsSwipeUpHandler<T extends StatefulActivity<S>,
         if (DesktopTaskView.DESKTOP_MODE_SUPPORTED && targets.hasDesktopTasks()) {
             mRemoteTargetHandles = mTargetGluer.assignTargetsForDesktop(targets);
         } else {
+            int untrimmedAppCount = mRemoteTargetHandles.length;
             mRemoteTargetHandles = mTargetGluer.assignTargetsForSplitScreen(targets);
+            if (mRemoteTargetHandles.length < untrimmedAppCount && mIsSwipeForSplit) {
+                updateIsGestureForSplit(mRemoteTargetHandles.length);
+                setupRecentsViewUi();
+            }
         }
         mRecentsAnimationController = controller;
         mRecentsAnimationTargets = targets;