Drop duplicated path separater at #include

Tbr: dcheng@chromium.org, falken@chromium.org, haraken@chromium.org
Change-Id: I7a9e81b2a3f186d373686391d67bcbb56846245b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1578150
Reviewed-by: Taiju Tsuiki <tzik@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653159}
3 files changed