Add ResetModem method and call it once non_cellular activation is done.

chrome/browser/chromeos/mobile/mobile_activator.cc

Index: chrome/browser/chromeos/mobile/mobile_activator.cc
diff --git a/chrome/browser/chromeos/mobile/mobile_activator.cc b/chrome/browser/chromeos/mobile/mobile_activator.cc
index 3fa1a4d9b90d16838861ef5bbf72e24b15a305d1..71cb8f360ae1198f833613c539292dc317f28716 100644
--- a/chrome/browser/chromeos/mobile/mobile_activator.cc
+++ b/chrome/browser/chromeos/mobile/mobile_activator.cc
@@ -279,6 +279,8 @@ void MobileActivator::HandleSetTransactionStatus(bool success) {
     CellularNetwork* network = FindMatchingCellularNetwork(true);
     if (network && network->activate_over_non_cellular_network()) {
       state_ = PLAN_ACTIVATION_DONE;
+      // We're done with activation, reset the cellular device.
+      lib->ResetModem();
       EvaluateCellularNetwork(network);
     } else {
       StartOTASP();