Dragging in touch explore mode should not become exploring.

In touch exploration two fingers in the same direction drag and if one of them
goes up the other starts to touch explore. This however causes inadvertent touch
exploring to happen on almost every scroll causing confusion. Now two finger
drag and they should both go up to allow exploring. This way the inadvertent
exploring is gone and user experience is much better.

bug:5440411

Change-Id: Id8aaece92e5dea1fc740400d2adc9dd63a1674e4

Author: sganov

services/java/com/android/server/accessibility/TouchExplorer.java

@@ -457,6 +457,9 @@ private void handleMotionEventStateDragging(MotionEvent event, int policyFlags)
             case MotionEvent.ACTION_MOVE: {
                 final int activePointerCount = mPointerTracker.getActivePointerCount();
                 switch (activePointerCount) {
+                    case 1: {
+                        // do nothing
+                    } break;
                     case 2: {
                         if (isDraggingGesture(event)) {
                             // If still dragging send a drag event.
@@ -484,10 +487,12 @@ private void handleMotionEventStateDragging(MotionEvent event, int policyFlags)
                 }
             } break;
             case MotionEvent.ACTION_POINTER_UP: {
-                mCurrentState = STATE_TOUCH_EXPLORING;
                 // Send an event to the end of the drag gesture.
                 sendMotionEvent(event, MotionEvent.ACTION_UP, pointerIdBits, policyFlags);
              } break;
+            case MotionEvent.ACTION_UP: {
+                mCurrentState = STATE_TOUCH_EXPLORING;
+            } break;
             case MotionEvent.ACTION_CANCEL: {
                 clear();
             } break;
@@ -500,7 +505,7 @@ private void handleMotionEventStateDragging(MotionEvent event, int policyFlags)
      * @param event The event to be handled.
      * @param policyFlags The policy flags associated with the event.
      */
-    public void handleMotionEventStateDelegating(MotionEvent event, int policyFlags) {
+    private void handleMotionEventStateDelegating(MotionEvent event, int policyFlags) {
         switch (event.getActionMasked()) {
             case MotionEvent.ACTION_DOWN: {
                 throw new IllegalStateException("Delegating state can only be reached if "