Add RemoteDeviceLoader to create RemoteDevice from CryptAuth data.

components/proximity_auth/remote_device.cc

Index: components/proximity_auth/remote_device.cc
diff --git a/components/proximity_auth/remote_device.cc b/components/proximity_auth/remote_device.cc
index 378c2dfbd389563ce6fe159f83a0f71adb0d294a..af07da9870f80371891f4aa8d87dc88b08695273 100644
--- a/components/proximity_auth/remote_device.cc
+++ b/components/proximity_auth/remote_device.cc
@@ -8,11 +8,13 @@ namespace proximity_auth {
 
 RemoteDevice::RemoteDevice() {}
 
-RemoteDevice::RemoteDevice(const std::string& name,
+RemoteDevice::RemoteDevice(const std::string& user_id,
+                           const std::string& name,
                            const std::string& public_key,
                            const std::string& bluetooth_address,
                            const std::string& persistent_symmetric_key)
-    : name(name),
+    : user_id(user_id),
+      name(name),
       public_key(public_key),
       bluetooth_address(bluetooth_address),
       persistent_symmetric_key(persistent_symmetric_key) {}