The Xiaomi Mi 6 is a USB Power Delivery 3.0 enabled phone but let's see how it supports USB Power Delivery 2.0 based charging with the Google 45W USB-C Power Adapter that came with the Google Pixelbook.
Once we connected the Google 45W USB-C Power Adapter to the Mi 6 on a fully drained battery over USB Type-C, the voltage kept on ramping up and down over a 5 volts rail which at one point it went down to almost zero. Each time when reaching 5 volts, the charger automatically reset and started advertising its capabilities all over again thus restarting the charging sequencing. In between, the phone was not really able to pull current from the charger which resulted in almost no charging. Click here to download the trace captured by the GRL-A1 power analyzer to see more details.