Hmmm, I am not aware of anything different in in-browser discovery that would cause the app on the receiver to be terminated.

Is there anything that would cause the CastChannel to be torn-down or reset
in response to discovery events? e.g. if in-browser discovery is causing
more "device discovered" notifications, and that's causing the browser to
repeatedly re-connect to the device, might that cause the active
CastChannel to be dropped by the device?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/56a2b88da4ed8ab7bee6aab7d8e2e7f1397bf862

commit 56a2b88da4ed8ab7bee6aab7d8e2e7f1397bf862
Author: Bin Zhao <zhaobin@chromium.org>
Date: Wed Oct 18 17:21:38 2017

[Media Router] Remove sink from current_sinks_map_ only when all retry attempts fail

In existing code we remove a sink from |current_sinks_map_| when an open
channel request (single retry attempt) fails. It removes sinks and routes
from extension side, which may terminate Youtube session too early.
Changed it to remove sink only when all retry attempts fail.

Bug:  775244 
Change-Id: I7a881fdb15122a71a0963d9aee6c04744239828a
Reviewed-on: https://chromium-review.googlesource.com/722127
Commit-Queue: Bin Zhao <zhaobin@chromium.org>
Reviewed-by: Derek Cheng <imcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509800}
[modify] https://crrev.com/56a2b88da4ed8ab7bee6aab7d8e2e7f1397bf862/chrome/browser/media/router/discovery/mdns/cast_media_sink_service_impl.cc
[modify] https://crrev.com/56a2b88da4ed8ab7bee6aab7d8e2e7f1397bf862/chrome/browser/media/router/discovery/mdns/cast_media_sink_service_impl_unittest.cc

Please add appropriate OSs.

Your change meets the bar and is auto-approved for M63. Please go ahead and merge the CL to branch 3239 manually. Please contact milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), gkihumba@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Please merge your change to M63 branch 3239 before 4:00 PM PT today if possible, so we can take it in for next week last M63 dev release. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cbb4ca5bb96f39717d1f23870554c31b24daa5c1

commit cbb4ca5bb96f39717d1f23870554c31b24daa5c1
Author: Bin Zhao <zhaobin@chromium.org>
Date: Fri Oct 20 17:57:10 2017

[Media Router] Remove sink from current_sinks_map_ only when all retry attempts fail

In existing code we remove a sink from |current_sinks_map_| when an open
channel request (single retry attempt) fails. It removes sinks and routes
from extension side, which may terminate Youtube session too early.
Changed it to remove sink only when all retry attempts fail.

TBR=zhaobin@chromium.org

(cherry picked from commit 56a2b88da4ed8ab7bee6aab7d8e2e7f1397bf862)

Bug:  775244 
Change-Id: I7a881fdb15122a71a0963d9aee6c04744239828a
Reviewed-on: https://chromium-review.googlesource.com/722127
Commit-Queue: Bin Zhao <zhaobin@chromium.org>
Reviewed-by: Derek Cheng <imcheng@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#509800}
Reviewed-on: https://chromium-review.googlesource.com/730419
Reviewed-by: Bin Zhao <zhaobin@chromium.org>
Cr-Commit-Position: refs/branch-heads/3239@{#113}
Cr-Branched-From: adb61db19020ed8ecee5e91b1a0ea4c924ae2988-refs/heads/master@{#508578}
[modify] https://crrev.com/cbb4ca5bb96f39717d1f23870554c31b24daa5c1/chrome/browser/media/router/discovery/mdns/cast_media_sink_service_impl.cc
[modify] https://crrev.com/cbb4ca5bb96f39717d1f23870554c31b24daa5c1/chrome/browser/media/router/discovery/mdns/cast_media_sink_service_impl_unittest.cc