The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform/tast-tests/+/2e6fae72aa1b3fcff361ec9efe29e0058e4aab84

commit 2e6fae72aa1b3fcff361ec9efe29e0058e4aab84
Author: Shuhei Takahashi <nya@chromium.org>
Date: Wed Oct 31 15:17:30 2018

chrome: JavaScript console logger.

This logger saves JavaScript console logs of all attached Chrome tabs.

Two primary types are introduced:

- jslog.Master is associated with chrome.Chrome. It accumulates logs
  from jslog.Worker into memory and saves to a single file.
- jslog.Worker is associated with chrome.Conn. It watches console log
  events and transfers logs to jslog.Master.

BUG= chromium:888886 
TEST=fast_build.sh -T
TEST=Modified ui.ChromeLogin to emit logs and made sure logs are
     indeed saves to jslog.txt.

Change-Id: I146dc14ef6d0c73a63029083351d997f8ce42f4e
Reviewed-on: https://chromium-review.googlesource.com/1303786
Commit-Ready: Shuhei Takahashi <nya@chromium.org>
Tested-by: Shuhei Takahashi <nya@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>

[add] https://crrev.com/2e6fae72aa1b3fcff361ec9efe29e0058e4aab84/src/chromiumos/tast/local/chrome/jslog/jslog.go
[modify] https://crrev.com/2e6fae72aa1b3fcff361ec9efe29e0058e4aab84/src/chromiumos/tast/local/chrome/conn.go
[add] https://crrev.com/2e6fae72aa1b3fcff361ec9efe29e0058e4aab84/src/chromiumos/tast/local/chrome/jslog/jslog_test.go
[modify] https://crrev.com/2e6fae72aa1b3fcff361ec9efe29e0058e4aab84/src/chromiumos/tast/local/chrome/chrome.go