Fix crash when handling touch on caption

http://ag/20355140 moved drag detection outside the switch block.
It now can be true when we are not going to handle the touch.
Add extra check for mShouldHandleEvents before processing ACTION_UP or
ACTION_CANCEL.

Bug: 259297955
Test: touch down outside the window, in caption area, drag finger and
  release
Test: attach a bluetooth mouse and resize the window from sides
Change-Id: I6645479eb1709e68ade87d2d7e7babdf99f232aa

libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DragResizeInputListener.java

@@ -317,7 +317,7 @@ class DragResizeInputListener implements AutoCloseable {
                 }
                 case MotionEvent.ACTION_UP:
                 case MotionEvent.ACTION_CANCEL: {
-                    if (mDragging) {
+                    if (mShouldHandleEvents && mDragging) {
                         int dragPointerIndex = e.findPointerIndex(mDragPointerId);
                         mCallback.onDragResizeEnd(
                                 e.getRawX(dragPointerIndex), e.getRawY(dragPointerIndex));