shill: wimax: Ask for credentials after users explicitly disconnect from network.

BUG=None
TEST=Verify that UI prompts for credentials when reconnecting to a WiMAX
network after explicitly disconnecting from the network.

Change-Id: I2de1e1c22ca32c9afd01baafe53c8efcdcd6604e
Reviewed-on: https://gerrit.chromium.org/gerrit/24565
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Commit-Ready: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
diff --git a/wimax_service.cc b/wimax_service.cc
index ee0245b..c58fc95 100644
--- a/wimax_service.cc
+++ b/wimax_service.cc
@@ -162,6 +162,13 @@
   Service::Disconnect(error);
   device_->DisconnectFrom(this, error);
   device_ = NULL;
+  // Set |need_passphrase_| to true so that after users explicitly disconnect
+  // from the network, the UI will prompt for credentials when they try to
+  // re-connect to the same network. This works around the fact that there is
+  // currently no mechanism for changing credentials for WiMAX connections.
+  // TODO(benchan,petkov): Find a better way to allow users to change the
+  // EAP credentials.
+  need_passphrase_ = true;
 }
 
 string WiMaxService::GetStorageIdentifier() const {