[Android] Always cache local files.

It's best not to cache them on desktop, because someone might be
developing locally. On Android, that's not likely to be the case and
is a significant perf hit.

BUG=292959

Review URL: https://chromiumcodereview.appspot.com/23431035

git-svn-id: svn://svn.chromium.org/blink/trunk@157991 bbb929c8-8fbe-4397-9dbb-9b2b20218538