Steps to reproduce the problem:
https://plus.google.com/+KostyaVasilyev/posts/1vBCKw8JVs3

1. Android 6.0.1 (Nexus 5, stock M4B30Z)
2. WebView beta (65.0.3325.38) updated a day or two ago

3. Desktop (Linux x64) Chrome (64.0.3282.140)
4. On Android: app(s) using WebView, enabling WebView debugging
5. In Linux Chrome: chrome://inspect, try to open the Android WebView ver 65

What is the expected behavior?
Dev tools in Chrome 64 able to connect to WebView 65 on Android

What went wrong?
Dev tools' new window opens, but never completes loading and never shows actual Dev Tools inspectors.

chrome-devtools://devtools/remote/....

Did this work before? Yes Android WebView 64

Chrome version: 65.0.3325.38  Channel: beta
OS Version: 6.0
Flash Version: N/A

Leaving WebView beta and downgrading to stable WebView ver. 64 made Dev Tools work again.

Maybe this is a known limitation because of a protocol change, if so it would make sense to show a notice (in Chrome on the host system where I'm opening dev tools).

Or maybe this is an unintentional regression, don't know. Whatever the reason, Android WebView ver. 65 + desktop Chrome ver. 64 -> chrome://inspect into Android WebView is broken.