A file is strongly associated with a view, and knows how to manage it's own
contents.
We can also now track files that are not "active"
Change-Id: Ib9474cd40e5caa3db6596548612a9f90168b8a19
Reviewed-on: https://go-review.googlesource.com/c/147204
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
