[CrOS Tether] TetherHostFetcher: When invoking callbacks, use a copy of the device list.

chromeos/components/tether/tether_host_fetcher.cc

Index: chromeos/components/tether/tether_host_fetcher.cc
diff --git a/chromeos/components/tether/tether_host_fetcher.cc b/chromeos/components/tether/tether_host_fetcher.cc
index 6f5427a188e040c12f95e00ab7320a94a5ea436b..f033cf92c55fb1ed17c4b54fdfc77fbcdc62129f 100644
--- a/chromeos/components/tether/tether_host_fetcher.cc
+++ b/chromeos/components/tether/tether_host_fetcher.cc
@@ -85,7 +85,7 @@ void TetherHostFetcher::OnRemoteDevicesLoaded(
     if (request.device_id.empty()) {
       DCHECK(!request.list_callback.is_null());
 
-      request.list_callback.Run(remote_devices);
+      request.list_callback.Run(remote_devices_copy);
       continue;
     }