Fix against accessibility event callback calling itself.

        @Override

        public void run() {

            // mSource may be changed in calls below.

            View source = mSource;

            mSource = null;

            // The accessibility may be turned off while we were waiting so check again.

            if (AccessibilityManager.getInstance(mContext).isEnabled()) {

                mLastEventTimeMillis = SystemClock.uptimeMillis();

                AccessibilityEvent event = AccessibilityEvent.obtain();

                event.setEventType(AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);

                event.setContentChangeTypes(mChangeTypes);

                mSource.sendAccessibilityEventUnchecked(event);

                source.sendAccessibilityEventUnchecked(event);

            } else {

                mLastEventTimeMillis = 0;

            }

            // In any case reset to initial state.

            mSource.resetSubtreeAccessibilityStateChanged();

            mSource = null;

            source.resetSubtreeAccessibilityStateChanged();

            mChangeTypes = 0;

        }