Looks like we're getting a 404 back from logs.chromium.org, could be propagation delay. 

Request to https://logs.chromium.org/prpc/logdog.Logs/Get resulted in 404, headers:[["content-length", "15"], ["via", "1.1 google"], ["server", "nginx"], ["x-prpc-grpc-code", "5"], ["date", "Wed, 15 Nov 2017 06:42:38 GMT"], ["content-type", "text/plain"]]

context:
E  GET 200 84 B 2.1 s AppEngine-Google; (+http://code.google.com/appengine) /_ah/pipeline/callback?callback_params=%7B%22backoff_time%22%3A+120%2C+%22max_error_times%22%3A+5%2C+%22default_pipeline_wait_seconds%22%3A+120%2C+%22deadline%22%3A+1510763088.14961%2C+%22urlsafe_try_job_key%22%3A+%22ag9zfmZpbmRpdC1mb3ItbWVy7QELEgtGbGFrZVRyeUpvYiLbAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzIChkYmcpKDEpKDMyKS9icm93c2VyX3Rlc3RzL1FuSnZkM05sY2tOc2IzTmxUV0Z1WVdkbGNrSnliM2R6WlhKVVpYTjBMMEp5YjNkelpYSkRiRzl6WlUxaGJtRm5aWEpDY205M2MyVnlWR1Z6ZEM1QlpHUkNaV1p2Y21WVmJteHZZV1JFZFhKcGJtZERiRzl6YVc1bkx6QT0vY2ZlZjY0NTE5OTZiZGQ2ZTk5YzI4ODA0N2QzMDY3ZTRiMDUxZjNlMww%22%2C+%22try_job_type%22%3A+18%2C+%22timeout_hours%22%3A+10%2C+%22try_job_id%22%3A+%228962881549635518656%22%2C+%22already_set_started%22%3A+true%2C+%22error_count%22%3A+0%7D&pipeline_id=bdcd1da3dc9a43818d50786163635113 GET 200 84 B 2.1 s AppEngine-Google; (+http://code.google.com/appengine) 5a0be1de00ff05c598206206e90001737e66696e6469742d666f722d6d650001776174657266616c6c2d6261636b656e643a31323734362d66623665393566000100
  0.1.0.2 - - [14/Nov/2017:22:42:38 -0800] "GET /_ah/pipeline/callback?callback_params=%7B%22backoff_time%22%3A+120%2C+%22max_error_times%22%3A+5%2C+%22default_pipeline_wait_seconds%22%3A+120%2C+%22deadline%22%3A+1510763088.14961%2C+%22urlsafe_try_job_key%22%3A+%22ag9zfmZpbmRpdC1mb3ItbWVy7QELEgtGbGFrZVRyeUpvYiLbAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzIChkYmcpKDEpKDMyKS9icm93c2VyX3Rlc3RzL1FuSnZkM05sY2tOc2IzTmxUV0Z1WVdkbGNrSnliM2R6WlhKVVpYTjBMMEp5YjNkelpYSkRiRzl6WlUxaGJtRm5aWEpDY205M2MyVnlWR1Z6ZEM1QlpHUkNaV1p2Y21WVmJteHZZV1JFZFhKcGJtZERiRzl6YVc1bkx6QT0vY2ZlZjY0NTE5OTZiZGQ2ZTk5YzI4ODA0N2QzMDY3ZTRiMDUxZjNlMww%22%2C+%22try_job_type%22%3A+18%2C+%22timeout_hours%22%3A+10%2C+%22try_job_id%22%3A+%228962881549635518656%22%2C+%22already_set_started%22%3A+true%2C+%22error_count%22%3A+0%7D&pipeline_id=bdcd1da3dc9a43818d50786163635113 HTTP/1.1" 200 84 https://findit-for-me.appspot.com/pubsub/tryjobpush "AppEngine-Google; (+http://code.google.com/appengine)" "12746-fb6e95f.waterfall-backend.findit-for-me.appspot.com" ms=2142 cpu_ms=79 cpm_usd=2.34805e-7 loading_request=0 instance=00c61b117c53fb468a750b294b35519e6bfb609ca8c91b5514afa282666f7493c7f1a0ff9ba4 app_engine_release=1.9.54 trace_id=-
I  GET 200 84 B 366 ms AppEngine-Google; (+http://code.google.com/appengine) /_ah/pipeline/callback?callback_params=%7B%22backoff_time%22%3A+120%2C+%22max_error_times%22%3A+5%2C+%22default_pipeline_wait_seconds%22%3A+120%2C+%22deadline%22%3A+1510763088.14961%2C+%22urlsafe_try_job_key%22%3A+%22ag9zfmZpbmRpdC1mb3ItbWVy7QELEgtGbGFrZVRyeUpvYiLbAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzIChkYmcpKDEpKDMyKS9icm93c2VyX3Rlc3RzL1FuSnZkM05sY2tOc2IzTmxUV0Z1WVdkbGNrSnliM2R6WlhKVVpYTjBMMEp5YjNkelpYSkRiRzl6WlUxaGJtRm5aWEpDY205M2MyVnlWR1Z6ZEM1QlpHUkNaV1p2Y21WVmJteHZZV1JFZFhKcGJtZERiRzl6YVc1bkx6QT0vY2ZlZjY0NTE5OTZiZGQ2ZTk5YzI4ODA0N2QzMDY3ZTRiMDUxZjNlMww%22%2C+%22try_job_type%22%3A+18%2C+%22timeout_hours%22%3A+10%2C+%22try_job_id%22%3A+%228962881549635518656%22%2C+%22already_set_started%22%3A+false%2C+%22error_count%22%3A+0%7D&pipeline_id=bdcd1da3dc9a43818d50786163635113 GET 200 84 B 366 ms AppEngine-Google; (+http://code.google.com/appengine) 5a0bddde00ff0647d12b1b8c830001737e66696e6469742d666f722d6d650001776174657266616c6c2d6261636b656e643a31323734362d66623665393566000100
  0.1.0.2 - - [14/Nov/2017:22:25:34 -0800] "GET /_ah/pipeline/callback?callback_params=%7B%22backoff_time%22%3A+120%2C+%22max_error_times%22%3A+5%2C+%22default_pipeline_wait_seconds%22%3A+120%2C+%22deadline%22%3A+1510763088.14961%2C+%22urlsafe_try_job_key%22%3A+%22ag9zfmZpbmRpdC1mb3ItbWVy7QELEgtGbGFrZVRyeUpvYiLbAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzIChkYmcpKDEpKDMyKS9icm93c2VyX3Rlc3RzL1FuSnZkM05sY2tOc2IzTmxUV0Z1WVdkbGNrSnliM2R6WlhKVVpYTjBMMEp5YjNkelpYSkRiRzl6WlUxaGJtRm5aWEpDY205M2MyVnlWR1Z6ZEM1QlpHUkNaV1p2Y21WVmJteHZZV1JFZFhKcGJtZERiRzl6YVc1bkx6QT0vY2ZlZjY0NTE5OTZiZGQ2ZTk5YzI4ODA0N2QzMDY3ZTRiMDUxZjNlMww%22%2C+%22try_job_type%22%3A+18%2C+%22timeout_hours%22%3A+10%2C+%22try_job_id%22%3A+%228962881549635518656%22%2C+%22already_set_started%22%3A+false%2C+%22error_count%22%3A+0%7D&pipeline_id=bdcd1da3dc9a43818d50786163635113 HTTP/1.1" 200 84 https://findit-for-me.appspot.com/pubsub/tryjobpush "AppEngine-Google; (+http://code.google.com/appengine)" "12746-fb6e95f.waterfall-backend.findit-for-me.appspot.com" ms=366 cpu_ms=108 cpm_usd=6.6496e-8 loading_request=0 instance=00c61b117c829371898832dc9595f6252330952264dfbc860e98a25eeb1069c5d851ed482820 app_engine_release=1.9.54 trace_id=2aa0f62ea17017c73b71ad67e78cee7f
D  POST 200 84 B 231 ms AppEngine-Google; (+http://code.google.com/appengine) /_ah/pipeline/finalized POST 200 84 B 231 ms AppEngine-Google; (+http://code.google.com/appengine) 5a0bddb100ff02ec8058468ffb0001737e66696e6469742d666f722d6d650001776174657266616c6c2d6261636b656e643a31323734362d66623665393566000100
  0.1.0.2 - - [14/Nov/2017:22:24:49 -0800] "POST /_ah/pipeline/finalized HTTP/1.1" 200 84 http://12746-fb6e95f.waterfall-backend.findit-for-me.appspot.com/_ah/pipeline/output "AppEngine-Google; (+http://code.google.com/appengine)" "12746-fb6e95f.waterfall-backend.findit-for-me.appspot.com" ms=231 cpu_ms=336 cpm_usd=9.387e-9 loading_request=0 instance=00c61b117c829371898832dc9595f6252330952264dfbc860e98a25eeb1069c5d851ed482820 app_engine_release=1.9.54 trace_id=-
https://pantheon.corp.google.com/logs/viewer?project=findit-for-me&_ga=1.96030428.118927748.1494873512&minLogLevel=0&expandAll=false&timestamp=2017-11-15T06:42:38.378264000Z&dateRangeStart=2017-11-09T21:44:06.820Z&dateRangeEnd=2017-11-16T21:44:06.820Z&interval=P7D&resource=gae_app%2Fmodule_id%2Fwaterfall-backend%2Fversion_id%2F12746-fb6e95f&logName=projects%2Ffindit-for-me%2Flogs%2Fappengine.googleapis.com%252Frequest_log&filters=text:BrowserCloseManagerBrowserTest%2FBrowserCloseManagerBrowserTest.AddBeforeUnloadDuringClosing%2F0

We should probably retry this request with a backoff on it. This is part of a larger issue where our network requests are quite flimsy.