Intercept abnormal MotionEvent in GestureDetector#onTouchEvent

This could happen if an app started to send events to
GestureDetector.onTouchEvent without sending an ACTION_DOWN event first.
GestureDetector must see a complete event stream for a gesture to behave
correctly. A complete event stream is defined as:
-One ACTION_DOWN event
-Zero or more ACTION_MOVE events and matched pairs of
ACTION_POINTER_DOWN/ACTION_POINTER_UP
-One ACTION_UP or ACTION_CANCEL

Bug: 242021191
Test: run cts -m CtsViewTestCases -t android.view.cts.GestureDetectorTest

Change-Id: I22a5d1c162885d08ee7dfe9deef2aed0ed801d16
Signed-off-by: huyuxin <huyuxin@xiaomi.corp-partner.google.com>

core/java/android/view/GestureDetector.java

@@ -653,7 +653,7 @@ public class GestureDetector {
                 break;
 
             case MotionEvent.ACTION_MOVE:
-                if (mInLongPress || mInContextClick) {
+                if ((mCurrentDownEvent == null) || mInLongPress || mInContextClick) {
                     break;
                 }
 
@@ -736,6 +736,9 @@ public class GestureDetector {
                 break;
 
             case MotionEvent.ACTION_UP:
+                if (mCurrentDownEvent == null) {
+                    break;
+                }
                 mStillDown = false;
                 MotionEvent currentUpEvent = MotionEvent.obtain(ev);
                 if (mIsDoubleTapping) {