Add Mojo IPC based input-device service.

ui/events/devices/mojo/input_devices.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 ui.mojom;
+
+import "ui/gfx/geometry/mojo/geometry.mojom";
+
+// Corresponds to ui::InputDeviceType
+enum InputDeviceType {
+  INPUT_DEVICE_INTERNAL,
+  INPUT_DEVICE_EXTERNAL,
+  INPUT_DEVICE_UNKNOWN,
+};
+
+// Corresponds to ui::InputDevice.
+struct InputDevice {
+  int32 id;
+  InputDeviceType type;
+  string name;
+  string sys_path;
+  uint16 vendor_id;
+  uint16 product_id;
+};
+
+// Corresponds to ui::TouchscreenDevice.
+struct TouchscreenDevice {
+  // Base class.
+  InputDevice input_device;
+
+  gfx.mojom.Size size;
+  int32 touch_points;
+};