Add Mojo IPC based input-device service.

components/mus/input_devices/input_device_struct_traits.h

Index: components/mus/input_devices/input_device_struct_traits.h
diff --git a/components/mus/input_devices/input_device_struct_traits.h b/components/mus/input_devices/input_device_struct_traits.h
new file mode 100644
index 0000000000000000000000000000000000000000..41434011560005f84f2faf51ae08357c77cdb96f
--- /dev/null
+++ b/components/mus/input_devices/input_device_struct_traits.h
@@ -0,0 +1,81 @@
+// 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.
+
+#ifndef COMPONENTS_MUS_INPUT_DEVICES_INPUT_DEVICE_STRUCT_TRAITS_H_
+#define COMPONENTS_MUS_INPUT_DEVICES_INPUT_DEVICE_STRUCT_TRAITS_H_
+
+#include <string>
+
+#include "base/strings/string_piece.h"
+#include "components/mus/public/interfaces/input_devices/input_devices.mojom.h"
+#include "ui/events/devices/input_device.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<input_device::mojom::InputDevice, ui::InputDevice> {
+  static int32_t id(const ui::InputDevice& device) { return device.id; }
+
+  static input_device::mojom::InputDeviceType type(
+      const ui::InputDevice& device) {
+    switch (device.type) {
+      case ui::INPUT_DEVICE_INTERNAL:
+        return input_device::mojom::InputDeviceType::INPUT_DEVICE_INTERNAL;
+      case ui::INPUT_DEVICE_EXTERNAL:
+        return input_device::mojom::InputDeviceType::INPUT_DEVICE_EXTERNAL;
+      case ui::INPUT_DEVICE_UNKNOWN:
+        return input_device::mojom::InputDeviceType::INPUT_DEVICE_UNKNOWN;
+    }
+  }
+
+  static std::string name(const ui::InputDevice& device) { return device.name; }

[sadrul, 2016/06/07 03:39:25]

Can the return type be const-ref in struct-traits?

[kylechar, 2016/06/07 16:36:41]

I don't see why not. Done.

+
+  static base::StringPiece sys_path(const ui::InputDevice& device) {
+    return device.sys_path.AsUTF8Unsafe();
+  }
+
+  static uint32_t vendor_id(const ui::InputDevice& device) {
+    return device.vendor_id;
+  }
+
+  static uint32_t product_id(const ui::InputDevice& device) {
+    return device.product_id;
+  }
+
+  static bool Read(input_device::mojom::InputDeviceDataView data,
+                   ui::InputDevice* out) {
+    out->id = data.id();
+
+    switch (data.type()) {
+      case input_device::mojom::InputDeviceType::INPUT_DEVICE_INTERNAL:
+        out->type = ui::INPUT_DEVICE_INTERNAL;
+        break;
+      case input_device::mojom::InputDeviceType::INPUT_DEVICE_EXTERNAL:
+        out->type = ui::INPUT_DEVICE_EXTERNAL;
+        break;
+      case input_device::mojom::InputDeviceType::INPUT_DEVICE_UNKNOWN:
+        out->type = ui::INPUT_DEVICE_UNKNOWN;
+        break;
+      default:

[sadrul, 2016/06/07 03:39:25]

Remove default case?

[kylechar, 2016/06/07 16:36:41]

Do we want that? We can't necessarily control what data we receive to
deserialize, so it's possible an invalid enum value might be there? I'm not
totally sure what the best practice is here.

[sadrul, 2016/06/08 16:31:09]

Hm, good point. I was going for the 'omit default: so if there are new enums,
compiler tells us to update the code' benefit, but you raise a good point.
Perhaps tsepez@ can suggest if this is OK?

+        return false;
+    }
+
+    if (!data.ReadName(&out->name))
+      return false;
+
+    base::StringPiece sys_path_string;
+    if (!data.ReadSysPath(&sys_path_string))
+      return false;
+    out->sys_path = base::FilePath::FromUTF8Unsafe(sys_path_string);
+
+    out->vendor_id = data.vendor_id();
+    out->product_id = data.product_id();
+
+    return true;
+  }
+};
+
+}  // namespace mojo
+
+#endif  // COMPONENTS_MUS_INPUT_DEVICES_INPUT_DEVICE_STRUCT_TRAITS_H_