Version: 54.0.2830.0 
OS: Chrome 8718.0.0 dev

What steps will reproduce the problem?
1. Join a two way successful hangout call between a  chrome device user and Linux desktop user
2. From chrome device user, select the 'screenshare' option from the list shown on the left side of the hangout window
3. Select any available window for screensharing and click on 'Screenshare'
4. Observe that :
a) hangout window displays "You are screensharing" followed by two buttons "Stop" and "Present to everyone"
b) an overlay dialog box is displayed in the lower right-hand side of the hangout window "Google Hangouts is sharing your screen with hangouts.google.com" followed by a "Stop" button
c) device shared screen is displayed on desktop user screen
5. Now click on "Stop" in hangouts overlay dialog box (Step 4b) 

Expected result:
a) Screensharing should stop and desktop user screen should display the images sent by device camera.
b) Remote video thumbnail preview should display images sent by device camera

Actual result:
a) Screensharing pauses on desktop user screen instead of stopping the screensharing
b) Remote video thumbnail preview displays a blank screen

Notes:
1. Screensharing stops as expected when user clicks on "Stop" button in hangouts window
2. This issue is not observed in M53 beta (53.0.2785.55 / 8530.49.0)
3. Feedback submitted for this issue:
https://feedback.corp.google.com/product/208/neutron?lView=rd&lRSort=1&lROrder=2&lRFilter=1&lReportSearch=user:srcv&lReport=17094254916