Check if the sc is valid when finishing seamless rotation

If the window is removed, the finish seamless rotation can be
triggered from the blast sync timeout.

Bug: 182738086
Test: repro steps in bug does not repro anymore
Change-Id: I87bef0dbddeb5640e356afb2d2e57334b8690c28

services/core/java/com/android/server/wm/SeamlessRotator.java

@@ -102,6 +102,10 @@ public class SeamlessRotator {
      * window in the new orientation.
      */
     void finish(Transaction t, WindowContainer win) {
+        if (win.mSurfaceControl == null || !win.mSurfaceControl.isValid()) {
+            return;
+        }
+
         mTransform.reset();
         t.setMatrix(win.mSurfaceControl, mTransform, mFloat9);
         t.setPosition(win.mSurfaceControl, win.mLastSurfacePosition.x, win.mLastSurfacePosition.y);