Add RemoteDeviceLoader to create RemoteDevice from CryptAuth data.

components/proximity_auth/device_to_device_authenticator_unittest.cc

Index: components/proximity_auth/device_to_device_authenticator_unittest.cc
diff --git a/components/proximity_auth/device_to_device_authenticator_unittest.cc b/components/proximity_auth/device_to_device_authenticator_unittest.cc
index 17c260c826dbdace7a800e9384601b7771a83f5f..7386aaddaef8c65811ae6c347b6b32faed7a5a9b 100644
--- a/components/proximity_auth/device_to_device_authenticator_unittest.cc
+++ b/components/proximity_auth/device_to_device_authenticator_unittest.cc
@@ -25,6 +25,7 @@ namespace {
 const char kAccountId[] = "example@gmail.com";
 
 // Attributes of the connected remote device.
+const char kRemoteDeviceUserId[] = "example@gmail.com";
 const char kRemoteDeviceName[] = "iPhone 6";
 const char kRemoteDevicePublicKey[] = "remote public key";
 const char kRemoteDeviceBluetoothAddress[] = "AA:BB:CC:DD:EE:FF";
@@ -138,7 +139,8 @@ class DeviceToDeviceAuthenticatorForTest : public DeviceToDeviceAuthenticator {
 class ProximityAuthDeviceToDeviceAuthenticatorTest : public testing::Test {
  public:
   ProximityAuthDeviceToDeviceAuthenticatorTest()
-      : remote_device_(kRemoteDeviceName,
+      : remote_device_(kRemoteDeviceUserId,
+                       kRemoteDeviceName,
                        kRemoteDevicePublicKey,
                        kRemoteDeviceBluetoothAddress,
                        kRemoteDevicePersistentSymmetricKey),