Version: 52.0.2743.32 (Official Build) dev (32-bit)
OS: ChromeOS 8350.21.1 (Official Build) dev-channel veyron_minnie

What steps will reproduce the problem?
(1) Open hangouts app https://chrome.google.com/webstore/detail/google-hangouts/knipolnnllmklapflnccelgolnpehhpl
(2) Open a conversation (with history)
(3) Try to use the touchpad to scroll up in the history.

What is the expected output?
Expect conversation history to scroll.

What do you see instead?
Instead, while fingers are on the touchpad the history does not scroll. It only scrolls after fingers are released if a fling was initiated.

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