bluetooth: Use BluetoothUUID instead of string when sending uuids

device/bluetooth/public/interfaces/bluetooth_uuid_struct_traits.h

+// 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 DEVICE_BLUETOOTH_PUBLIC_INTERFACES_BLUETOOTH_UUID_STRUCT_TRAITS_H_
+#define DEVICE_BLUETOOTH_PUBLIC_INTERFACES_BLUETOOTH_UUID_STRUCT_TRAITS_H_
+
+#include "base/optional.h"
+#include "base/strings/string_piece.h"
+#include "device/bluetooth/bluetooth_uuid.h"
+#include "device/bluetooth/public/interfaces/bluetooth_uuid.mojom.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<device::mojom::BluetoothUUID,
+                    base::Optional<device::BluetoothUUID>> {
+  static bool IsNull(const base::Optional<device::BluetoothUUID>& uuid) {
+    return !uuid;
+  }
+
+  static void SetToNull(base::Optional<device::BluetoothUUID>* output) {
+    *output = base::nullopt;
+  }
+
+  static base::StringPiece uuid(

[yzshen1, 2016/06/01 16:12:59]

nit: you could simply use static const std::string& uuid(...) { return
uuid->canonical_value(); }

(Actually you can use any type that has a StringTraits defined.)

Similarly, you can directly read a std::string from ReadUuid on line 36.

[ortuno, 2016/06/01 18:28:12]

Nice. Done.

+      const base::Optional<device::BluetoothUUID>& uuid) {
+    DCHECK(uuid);
+    return base::StringPiece(uuid->canonical_value().c_str(),
+                             uuid->canonical_value().length());
+  }
+
+  static bool Read(device::mojom::BluetoothUUIDDataView input,
+                   base::Optional<device::BluetoothUUID>* output) {
+    base::StringPiece result;
+    if (!input.ReadUuid(&result))
+      return false;
+    *output = base::make_optional(device::BluetoothUUID(result.as_string()));
+
+    // If the format isn't 128-bit, .value() would return a different answer
+    // than .canonical_value(). Then if browser-side code accidentally checks
+    // .value() against a 128-bit string literal, a hostile renderer could use
+    // the 16- or 32-bit format and evade the check.
+    return output->value().IsValid() &&
+           output->value().format() == device::BluetoothUUID::kFormat128Bit;
+  }
+};
+
+}  // namespace mojo
+
+#endif  // DEVICE_BLUETOOTH_PUBLIC_INTERFACES_BLUETOOTH_UUID_STRUCT_TRAITS_H_