Yoland showed me this and I verified this on both m50, m51 WebView, on Android L and N.

This is not observed on Chrome with the same version.

Steps to reproduce:
1. open a webview app to display a long web page
2. open chrome://inspect and inspect the webview
3. scroll the webview with the finger pressed on the screen.

Observed result:
the webview scrolls faster than the finger moves

Expected result:
the webview scrolling should stick with the finger.