TouchInteractionController: allow state transitions from STATE_DRAG.

This is necessary to make the drag -> delegate execution path work.
Bug: 159651900
Test: atest TouchInteractionControllerTest

Change-Id: Idfb5d5ea8290353a7f4dac9742826a38fdd17b04

core/java/android/accessibilityservice/TouchInteractionController.java

@@ -376,7 +376,7 @@ public final class TouchInteractionController {
             throw new IllegalStateException(
                     "State transitions are not allowed without first adding a callback.");
         }
-        if (mState != STATE_TOUCH_INTERACTING) {
+        if (mState != STATE_TOUCH_INTERACTING && mState != STATE_DRAGGING) {
             throw new IllegalStateException(
                     "State transitions are not allowed in " + stateToString(mState));
         }