File API: Remove empty //content/common/fileapi.

Bug: 611935
Change-Id: I1795886cefad11e6481fd3081346a9bfb43132e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1767597
Auto-Submit: Victor Costan <pwnall@chromium.org>
Commit-Queue: Darwin Huang <huangdarwin@chromium.org>
Reviewed-by: Darwin Huang <huangdarwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#690012}

content/common/fileapi/OWNERS

-file://content/browser/fileapi/OWNERS
-
-per-file *_messages*.h=set noparent
-per-file *_messages*.h=file://ipc/SECURITY_OWNERS
-
-# TEAM: storage-dev@chromium.org
-# COMPONENT: Blink>Storage>FileSystem