GitLab

- Remove unnecessary #include
- Remove unused |capture| member
- Update comments

Bug: 869257
Change-Id: Ia16c39bd31be1a0d38f67efe6823cb62229fe0c8
Reviewed-on: https://chromium-review.googlesource.com/1157947Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579720}