Send gesture cancellation on correct thread

CancellationSignal listener should be called on main thread instead of
Binder thread.

Fix: 275426397
Test: atest InputConnectionEndToEndTest
Change-Id: Ief253699d52a19fb36996dd1f6b3487a59f87526

core/java/android/view/inputmethod/RemoteInputConnectionImpl.java

@@ -424,12 +424,15 @@ final class RemoteInputConnectionImpl extends IRemoteInputConnection.Stub {
         });
     }
 
+    @Dispatching(cancellable = false)
     @Override
     public void cancelCancellationSignal(IBinder token) {
         if (mBeamer == null) {
             return;
         }
-        mBeamer.cancel(token);
+        dispatch(() -> {
+            mBeamer.cancel(token);
+        });
     }
 
     @Override