1) Add initialization error page; 2) Add connection error page.

components/pairing/bluetooth_host_pairing_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/pairing/bluetooth_host_pairing_controller.h"
 
 #include "base/bind.h"
 #include "base/hash.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
@@ skipping 290 matching lines @@
 }
 
 void BluetoothHostPairingController::OnSetError() {
   adapter_->RemovePairingDelegate(this);
   ChangeStage(STAGE_INITIALIZATION_ERROR);
 }
 
 void BluetoothHostPairingController::OnAcceptError(
     const std::string& error_message) {
   LOG(ERROR) << error_message;
+  ChangeStage(STAGE_CONTROLLER_CONNECTION_ERROR);
 }
 
 void BluetoothHostPairingController::OnSendError(
     const std::string& error_message) {
   LOG(ERROR) << error_message;
+  ChangeStage(STAGE_CONTROLLER_CONNECTION_ERROR);

[dzhioev (left Google), 2015/12/17 23:33:32]

I don't think we should call this if |enrollment_status_| is
ENROLLMENT_STATUS_ENROLLING or ENROLLMENT_STATUS_SUCCESS.

[xdai1, 2015/12/17 23:49:08]

Agreed. Addressed your comment.

 }
 
 void BluetoothHostPairingController::OnReceiveError(
     device::BluetoothSocket::ErrorReason reason,
     const std::string& error_message) {
   LOG(ERROR) << reason << ", " << error_message;
+  ChangeStage(STAGE_CONTROLLER_CONNECTION_ERROR);
 }
 
 void BluetoothHostPairingController::OnHostStatusMessage(
     const pairing_api::HostStatus& message) {
   NOTREACHED();
 }
 
 void BluetoothHostPairingController::OnConfigureHostMessage(
     const pairing_api::ConfigureHost& message) {
   ChangeStage(STAGE_SETUP_BASIC_CONFIGURATION);
@@ skipping 13 matching lines @@
   ChangeStage(STAGE_ENROLLING);
   FOR_EACH_OBSERVER(Observer, observers_,
                     EnrollHostRequested(
                         message.parameters().admin_access_token()));
 }
 
 void BluetoothHostPairingController::OnCompleteSetupMessage(
     const pairing_api::CompleteSetup& message) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (current_stage_ != STAGE_ENROLLMENT_SUCCESS) {
+    ChangeStage(STAGE_ENROLLMENT_ERROR);
     AbortWithError(PAIRING_ERROR_PAIRING_OR_ENROLLMENT, kErrorInvalidProtocol);
     return;
   }
 
   // TODO(zork): Handle adding another controller. (http://crbug.com/405757)
   ChangeStage(STAGE_FINISHED);
 }
 
 void BluetoothHostPairingController::OnErrorMessage(
     const pairing_api::Error& message) {
@@ skipping 139 matching lines @@
   ChangeStage(STAGE_WAITING_FOR_CODE_CONFIRMATION);
 }
 
 void BluetoothHostPairingController::AuthorizePairing(
     device::BluetoothDevice* device) {
   // Disallow unknown device.
   device->RejectPairing();
 }
 
 }  // namespace pairing_chromeos