Mojom interface for Preferences

services/preferences/public/interfaces/preferences.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 prefs.mojom;
+
+// A Preference could be one of several base types. PrefStore utilizes
+// base::Value to encompass these. TODO(jonross): create struct traits so that
+// we can pass base::Value via mojo.

[Ben Goodger (Google), 2016/09/08 17:40:08]

FYI, Ken tells me there's already param traits support for base::Value in
mojo/common.

[jonross, 2016/09/09 15:55:35]

Yeah there are apparently some of the base::Value subclasses there.

I'll add the others and update this mojom

+struct Preference {
+  enum PreferenceType { INT, STRING };
+
+  PreferenceType type;
+  uint32 integer_value_;
+  string? string_value_;
+};
+
+// Used to subscribe to preference changes within PreferenceManager. After
+// requesting to observe, the current values for all requested keys are sent.
+interface PreferenceObserver {
+  OnPreferencesChanged(map<string, Preference> preferences);
+};
+
+// Manages actual read/write of preference data. Accepts observers who subscribe
+// to preferences, notifying them of changes.
+interface PreferenceManager {
+  AddObserver(array<string> preferences, PreferenceObserver client);
+  SetPreferences(map<string, Preference> preferences);
+};