service worker: Remove "chromium" names from http/tests/serviceworker

The entire directory is all non-upstreamable tests now, so we don't need
"chromium" anymore. We had some file names prefixed with "chromium." and
subdirectories called "chromium". This was making some relative paths
complicated and and was confusing when some files had the prefix and
some didn't.

Bug: 688116
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: I873cee47baa0338f57af8c6d4b90caac7fdd3c04
Reviewed-on: https://chromium-review.googlesource.com/1020480
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552233}
127 files changed