Under mash the code in //ash runs out of process. Code in //chrome/browser
must use the mojo interfaces in //ash/public/interfaces to talk to ash.

We're still in the process of refactoring existing code, but new code
should use the mojo approach. Tighten DEPS on //ash to limit the number
of new references.

Also file bugs to refactor the existing areas.

BUG=678705
TEST=buildtools/checkdeps/checkdeps.py

Review-Url: https://codereview.chromium.org/2891923003
Cr-Commit-Position: refs/heads/master@{#475577}