This is happening again in https://chrome-swarming.appspot.com/task?id=3ec316ec19308b10&refresh=10&show_raw=1

Looking at the code, we did set a timeout limit for capturing screenshot (https://cs.chromium.org/chromium/src/third_party/catapult/telemetry/telemetry/internal/browser/tab.py?rcl=f5342c4cf3d3e85e43be84c22bdfd8ebff23ec70&l=113). Seems like the timeout setting of websocket client is not super reliable.

The following revision refers to this bug:
  https://chromium.googlesource.com/catapult/+/9e2d298d8bc90fbc4589322b329827a9010362c9

commit 9e2d298d8bc90fbc4589322b329827a9010362c9
Author: nednguyen <nednguyen@google.com>
Date: Wed Jul 18 01:16:31 2018

Implement screenshot capturing at system level on Linux


Bug:  chromium:862996 
Change-Id: Ie8ec78086dfe8b26709c7b64b11301d39fcf7300
TBR=perezju@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/1141329
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>

[modify] https://crrev.com/9e2d298d8bc90fbc4589322b329827a9010362c9/telemetry/telemetry/core/platform_unittest.py
[modify] https://crrev.com/9e2d298d8bc90fbc4589322b329827a9010362c9/telemetry/telemetry/internal/platform/linux_platform_backend.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ee1d7d6a10afc8d71253cb849ed508f706cf92a9

commit ee1d7d6a10afc8d71253cb849ed508f706cf92a9
Author: catapult-chromium-autoroll <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Wed Jul 18 07:21:37 2018

Roll src/third_party/catapult f5342c4cf3d3..e8dc05ccba6b (9 commits)

https://chromium.googlesource.com/catapult.git/+log/f5342c4cf3d3..e8dc05ccba6b


git log f5342c4cf3d3..e8dc05ccba6b --date=short --no-merges --format='%ad %ae %s'
2018-07-18 nednguyen@google.com Revert "Handle stale directories when pushing files"
2018-07-18 nednguyen@google.com Implement screenshot capturing at system level on Linux
2018-07-17 dtu@chromium.org [pinpoint] Case-insensitive compare for Webview.
2018-07-17 simonhatch@chromium.org Dashboard - Whitelist documentation urls in /add_histograms
2018-07-17 cphlipot0@gmail.com [Systrace] Raise error when specified device is not found
2018-07-17 nednguyen@google.com Add test that verifies the way Telemetry generate skipped entries for filtered stories when benchmark is interrupted
2018-07-17 xiaochengh@chromium.org Disable WebPageReplayGoServerTest.testSmokeStartingWebPageReplayGoServer on Windows
2018-07-16 dtu@chromium.org [pinpoint] Update list of bots available in Pinpoint.
2018-07-16 bsheedy@chromium.org Handle stale directories when pushing files


Created with:
  gclient setdep -r src/third_party/catapult@e8dc05ccba6b

The AutoRoll server is located here: https://catapult-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel

BUG= chromium:862845 , chromium:862996 , chromium:863861 , chromium:860091 ,chromium:864294, chromium:863995 , chromium:862845 
TBR=sullivan@chromium.org

Change-Id: I5cab2a67db2dfee8c71f9ed7e445b82a9df41aec
Reviewed-on: https://chromium-review.googlesource.com/1141465
Reviewed-by: catapult-chromium-autoroll <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: catapult-chromium-autoroll <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#575965}
[modify] https://crrev.com/ee1d7d6a10afc8d71253cb849ed508f706cf92a9/DEPS

The following revision refers to this bug:
  https://chromium.googlesource.com/catapult/+/2ec2b508e61067ba5bfaf79ecc2e3b1dc79971d1

commit 2ec2b508e61067ba5bfaf79ecc2e3b1dc79971d1
Author: nednguyen <nednguyen@google.com>
Date: Thu Jul 19 13:08:05 2018

Update screenshot taking method on Linux to use gnome-screenshot

Verified that this produces an actual screenshot on my Linux machine

Bug:  chromium:862996 
Change-Id: I67559e2a238a9f99e1df1fce9b0b758a59dcb846
TBR=perezju@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/1143134
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>

[modify] https://crrev.com/2ec2b508e61067ba5bfaf79ecc2e3b1dc79971d1/telemetry/telemetry/internal/platform/linux_platform_backend.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b9c8982efbc6f4002524b12af48b758ef3a97240

commit b9c8982efbc6f4002524b12af48b758ef3a97240
Author: catapult-chromium-autoroll <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Thu Jul 19 14:11:04 2018

Roll src/third_party/catapult c3318d5f367c..2ec2b508e610 (1 commits)

https://chromium.googlesource.com/catapult.git/+log/c3318d5f367c..2ec2b508e610


git log c3318d5f367c..2ec2b508e610 --date=short --no-merges --format='%ad %ae %s'
2018-07-19 nednguyen@google.com Update screenshot taking method on Linux to use gnome-screenshot


Created with:
  gclient setdep -r src/third_party/catapult@2ec2b508e610

The AutoRoll server is located here: https://catapult-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel

BUG= chromium:862996 
TBR=sullivan@chromium.org

Change-Id: I009a3ce12d60d85f97ae4070ebd93c8c8a73594f
Reviewed-on: https://chromium-review.googlesource.com/1143031
Reviewed-by: catapult-chromium-autoroll <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: catapult-chromium-autoroll <catapult-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#576477}
[modify] https://crrev.com/b9c8982efbc6f4002524b12af48b758ef3a97240/DEPS

The system level screenshot is working on Linux now!

https://console.developers.google.com/m/cloudstorage/b/chrome-telemetry-output/o/9d9966de-8b81-11e8-85a4-509a4c653ad0