mojo: Sketch a profile application.

components/profile_service/public/interfaces/profile.mojom

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+module profile;
+
+import "components/filesystem/public/interfaces/directory.mojom";
+
+// An encapsulation around the per-profile storage to disk. A Profile is

[jam, 2016/02/27 01:34:45]

nit: we're going to add stuff to this later that's not just disk, so you can
skip the "storage to disk".

+// strongly bound to a User; during startup of the Profile process, we sandbox
+// the process so the only directory it has access to is the User's profile.
+interface ProfileService {
+  // Returns a directory specific to the Application identity of the caller.
+  GetDirectory(filesystem.Directory& dir);
+};