Reset cached values when reset divider position

We should reset these cached values when divider position reset
which should be called while split exiting.

Fix: 198557357
Test: pass exist tests
Test: manual
Change-Id: I1606ff785985752c2fd45df84a99979aa5063c64

libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitLayout.java

@@ -305,6 +305,10 @@ public final class SplitLayout implements DisplayInsetsController.OnInsetsChange
         mDividePosition = mDividerSnapAlgorithm.getMiddleTarget().position;
         mSplitWindowManager.setResizingSplits(false);
         updateBounds(mDividePosition);
+        mWinToken1 = null;
+        mWinToken2 = null;
+        mWinBounds1.setEmpty();
+        mWinBounds2.setEmpty();
     }
 
     /**