Move drag event to InputDispatcher (5/n)

This CL add 'notifyDropWindow' to tell the policy about the dropping
window has been detected. That could help the drag controller to handle
the drop event and dispatch the clip data to the corresponding client.

Bug: 158242495
Test: atest inputflinger_tests
Change-Id: If7bce072dff5bdacb7eb765f94eb73ed63a58170
diff --git a/services/inputflinger/dispatcher/include/InputDispatcherPolicyInterface.h b/services/inputflinger/dispatcher/include/InputDispatcherPolicyInterface.h
index 439d85e..219f45a 100644
--- a/services/inputflinger/dispatcher/include/InputDispatcherPolicyInterface.h
+++ b/services/inputflinger/dispatcher/include/InputDispatcherPolicyInterface.h
@@ -157,6 +157,9 @@
      * InputDispatcher is solely responsible for updating the Pointer Capture state.
      */
     virtual void setPointerCapture(bool enabled) = 0;
+
+    /* Notifies the policy that the drag window has moved over to another window */
+    virtual void notifyDropWindow(const sp<IBinder>& token, float x, float y) = 0;
 };
 
 } // namespace android