mus: Introduce high-contrast mode in mus.

services/ui/public/interfaces/accessibility_manager.mojom

Index: services/ui/public/interfaces/accessibility_manager.mojom
diff --git a/services/ui/public/interfaces/accessibility_manager.mojom b/services/ui/public/interfaces/accessibility_manager.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..94d9886fb92707e8adce30a49d4d068c3e90c1fe
--- /dev/null
+++ b/services/ui/public/interfaces/accessibility_manager.mojom
@@ -0,0 +1,13 @@
+// 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 ui.mojom;
+
+// Allows controlling accessibility in the UI service. Only one client at a time
+// can connect to AccessibilityManager. If a new client connects to it, then any
+// previously connected client is disconnected.
+interface AccessibilityManager {
+  // Enables (or disables) high contrast mode.
+  SetHighContrastMode(bool enabled);

[sadrul, 2016/07/08 16:22:18]

Would it make sense to have "enum ServiceState { ENABLE, DISABLE, TOGGLE };
SetHighContrastMode(ServiceState);" instead?

[sky, 2016/07/08 16:45:00]

Seems like the caller is going to know what state they want, right? When would
you envision TOGGLE being used?

[sadrul, 2016/07/08 17:33:25]

The system-tray gets an entry to toggle the flag, but it knows whether it is
turned on or not, so yeah, toggle doesn't actually need to be in the API.

+};