Handle no cellular device more gracefully in choose-mobile-network UI.

chrome/browser/ui/webui/chromeos/choose_mobile_network_ui.cc

Index: chrome/browser/ui/webui/chromeos/choose_mobile_network_ui.cc
diff --git a/chrome/browser/ui/webui/chromeos/choose_mobile_network_ui.cc b/chrome/browser/ui/webui/chromeos/choose_mobile_network_ui.cc
index 8ed5a8c360d09efdaa5fa3210f398f00cd357bac..7196f2cb69129a64f0dd82ab2d4304b7c29276a3 100644
--- a/chrome/browser/ui/webui/chromeos/choose_mobile_network_ui.cc
+++ b/chrome/browser/ui/webui/chromeos/choose_mobile_network_ui.cc
@@ -136,6 +136,9 @@ ChooseMobileNetworkHandler::ChooseMobileNetworkHandler()
     NET_LOG_ERROR(
         "A cellular device is not available.",
         "Cannot initiate a cellular network scan without a cellular device.");
+    // If there is no cellular device, we set |has_pending_results_| to true so
+    // that HandlePageReady() will show "No networks found." on the web UI.
+    has_pending_results_ = true;
     return;
   }
   handler->AddObserver(this, FROM_HERE);
@@ -221,6 +224,9 @@ void ChooseMobileNetworkHandler::HandleCancel(const base::ListValue* args) {
     return;
   }
 
+  if (device_path_.empty())
+    return;
+
   // Switch to automatic mode.
   GetNetworkDeviceHandler()->RegisterCellularNetwork(
       device_path_,