bluetooth: Shutdown BluetoothAdapter before DBus on ChromeOS.

device/bluetooth/bluetooth_adapter_chromeos.cc

 // Copyright 2013 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 "device/bluetooth/bluetooth_adapter_chromeos.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 54 matching lines @@
 }
 
 namespace chromeos {
 
 // static
 base::WeakPtr<BluetoothAdapter> BluetoothAdapterChromeOS::CreateAdapter() {
   BluetoothAdapterChromeOS* adapter = new BluetoothAdapterChromeOS();
   return adapter->weak_ptr_factory_.GetWeakPtr();
 }
 
+void BluetoothAdapterChromeOS::Shutdown() {
+  if (dbus_is_shutdown_)
+    return;
+  DCHECK(DBusThreadManager::IsInitialized())
+      << "Call BluetoothAdapterFactory::Shutdown() before "
+         "DBusThreadManager::Shutdown().";
+
+  if (IsPresent())
+    RemoveAdapter();  // Also deletes devices_.
+  DCHECK(devices_.empty());
+
+  DBusThreadManager::Get()->GetBluetoothAdapterClient()->RemoveObserver(this);
+  DBusThreadManager::Get()->GetBluetoothDeviceClient()->RemoveObserver(this);
+  DBusThreadManager::Get()->GetBluetoothInputClient()->RemoveObserver(this);
+
+  VLOG(1) << "Unregistering pairing agent";
+  DBusThreadManager::Get()->GetBluetoothAgentManagerClient()->UnregisterAgent(
+      dbus::ObjectPath(kAgentPath), base::Bind(&base::DoNothing),
+      base::Bind(&OnUnregisterAgentError));
+
+  agent_.reset();
+  dbus_is_shutdown_ = true;
+}
+
 BluetoothAdapterChromeOS::BluetoothAdapterChromeOS()
-    : num_discovery_sessions_(0),
+    : dbus_is_shutdown_(false),
+      num_discovery_sessions_(0),
       discovery_request_pending_(false),
       weak_ptr_factory_(this) {
   ui_task_runner_ = base::ThreadTaskRunnerHandle::Get();
   socket_thread_ = device::BluetoothSocketThread::Get();
 
   DBusThreadManager::Get()->GetBluetoothAdapterClient()->AddObserver(this);
   DBusThreadManager::Get()->GetBluetoothDeviceClient()->AddObserver(this);
   DBusThreadManager::Get()->GetBluetoothInputClient()->AddObserver(this);
 
   // Register the pairing agent.
   dbus::Bus* system_bus = DBusThreadManager::Get()->GetSystemBus();
   agent_.reset(BluetoothAgentServiceProvider::Create(
       system_bus, dbus::ObjectPath(kAgentPath), this));
   DCHECK(agent_.get());
 
   std::vector<dbus::ObjectPath> object_paths =
       DBusThreadManager::Get()->GetBluetoothAdapterClient()->GetAdapters();
 
   if (!object_paths.empty()) {
     VLOG(1) << object_paths.size() << " Bluetooth adapter(s) available.";
     SetAdapter(object_paths[0]);
   }
 }
 
 BluetoothAdapterChromeOS::~BluetoothAdapterChromeOS() {
-  DBusThreadManager::Get()->GetBluetoothAdapterClient()->RemoveObserver(this);
-  DBusThreadManager::Get()->GetBluetoothDeviceClient()->RemoveObserver(this);
-  DBusThreadManager::Get()->GetBluetoothInputClient()->RemoveObserver(this);
-
-  VLOG(1) << "Unregistering pairing agent";
-  DBusThreadManager::Get()->GetBluetoothAgentManagerClient()->
-      UnregisterAgent(
-          dbus::ObjectPath(kAgentPath),
-          base::Bind(&base::DoNothing),
-          base::Bind(&OnUnregisterAgentError));
+  Shutdown();
 }
 
 void BluetoothAdapterChromeOS::DeleteOnCorrectThread() const {
   if (ui_task_runner_->RunsTasksOnCurrentThread() ||
       !ui_task_runner_->DeleteSoon(FROM_HERE, this))
     delete this;
 }
 
 void BluetoothAdapterChromeOS::AddObserver(
     BluetoothAdapter::Observer* observer) {
@@ skipping 46 matching lines @@
                      weak_ptr_factory_.GetWeakPtr(),
                      callback,
                      error_callback));
 }
 
 bool BluetoothAdapterChromeOS::IsInitialized() const {
   return true;
 }
 
 bool BluetoothAdapterChromeOS::IsPresent() const {
-  return !object_path_.value().empty();
+  return !dbus_is_shutdown_ && !object_path_.value().empty();
 }
 
 bool BluetoothAdapterChromeOS::IsPowered() const {
   if (!IsPresent())
     return false;
 
   BluetoothAdapterClient::Properties* properties =
       DBusThreadManager::Get()->GetBluetoothAdapterClient()->
           GetProperties(object_path_);
 
@@ skipping 56 matching lines @@
           GetProperties(object_path_);
 
   return properties->discovering.value();
 }
 
 void BluetoothAdapterChromeOS::CreateRfcommService(
     const BluetoothUUID& uuid,
     const ServiceOptions& options,
     const CreateServiceCallback& callback,
     const CreateServiceErrorCallback& error_callback) {
+  DCHECK(!dbus_is_shutdown_);
   VLOG(1) << object_path_.value() << ": Creating RFCOMM service: "
           << uuid.canonical_value();
   scoped_refptr<BluetoothSocketChromeOS> socket =
       BluetoothSocketChromeOS::CreateBluetoothSocket(
           ui_task_runner_, socket_thread_);
   socket->Listen(this,
                  BluetoothSocketChromeOS::kRfcomm,
                  uuid,
                  options,
                  base::Bind(callback, socket),
                  error_callback);
 }
 
 void BluetoothAdapterChromeOS::CreateL2capService(
     const BluetoothUUID& uuid,
     const ServiceOptions& options,
     const CreateServiceCallback& callback,
     const CreateServiceErrorCallback& error_callback) {
+  DCHECK(!dbus_is_shutdown_);
   VLOG(1) << object_path_.value() << ": Creating L2CAP service: "
           << uuid.canonical_value();
   scoped_refptr<BluetoothSocketChromeOS> socket =
       BluetoothSocketChromeOS::CreateBluetoothSocket(
           ui_task_runner_, socket_thread_);
   socket->Listen(this,
                  BluetoothSocketChromeOS::kL2cap,
                  uuid,
                  options,
                  base::Bind(callback, socket),
                  error_callback);
 }
 
 void BluetoothAdapterChromeOS::RegisterAudioSink(
     const device::BluetoothAudioSink::Options& options,
     const device::BluetoothAdapter::AcquiredCallback& callback,
     const device::BluetoothAudioSink::ErrorCallback& error_callback) {
   // TODO(mcchou): Create and register a BluetoothAudioSink. Add the
   // newly-created audio sink as an observer of the adapter.
   // Add OnRegisterAudioSink(AcquiredCallback& , BluetoothAudioSink*) and pass
   // it as an argument to BluetoothAudioSinkChromeOS::Register.
   error_callback.Run(device::BluetoothAudioSink::ERRORCODE_NOT_SUPPORTED);
 }
 
 void BluetoothAdapterChromeOS::RemovePairingDelegateInternal(
     BluetoothDevice::PairingDelegate* pairing_delegate) {
+  DCHECK(IsPresent());
   // Before removing a pairing delegate make sure that there aren't any devices
   // currently using it; if there are, clear the pairing context which will
   // make any responses no-ops.
   for (DevicesMap::iterator iter = devices_.begin();
        iter != devices_.end(); ++iter) {
     BluetoothDeviceChromeOS* device_chromeos =
         static_cast<BluetoothDeviceChromeOS*>(iter->second);
 
     BluetoothPairingChromeOS* pairing = device_chromeos->GetPairing();
     if (pairing && pairing->GetPairingDelegate() == pairing_delegate)
@@ skipping 10 matching lines @@
 
 void BluetoothAdapterChromeOS::AdapterRemoved(
     const dbus::ObjectPath& object_path) {
   if (object_path == object_path_)
     RemoveAdapter();
 }
 
 void BluetoothAdapterChromeOS::AdapterPropertyChanged(
     const dbus::ObjectPath& object_path,
     const std::string& property_name) {
+  DCHECK(IsPresent());
   if (object_path != object_path_)
     return;
 
   BluetoothAdapterClient::Properties* properties =
       DBusThreadManager::Get()->GetBluetoothAdapterClient()->
           GetProperties(object_path_);
 
   if (property_name == properties->powered.name())
     PoweredChanged(properties->powered.value());
   else if (property_name == properties->discoverable.name())
     DiscoverableChanged(properties->discoverable.value());
   else if (property_name == properties->discovering.name())
     DiscoveringChanged(properties->discovering.value());
 }
 
 void BluetoothAdapterChromeOS::DeviceAdded(
   const dbus::ObjectPath& object_path) {
+  DCHECK(IsPresent());
   BluetoothDeviceClient::Properties* properties =
       DBusThreadManager::Get()->GetBluetoothDeviceClient()->
           GetProperties(object_path);
   if (properties->adapter.value() != object_path_)
     return;
 
   BluetoothDeviceChromeOS* device_chromeos =
       new BluetoothDeviceChromeOS(this,
                                   object_path,
                                   ui_task_runner_,
                                   socket_thread_);
   DCHECK(devices_.find(device_chromeos->GetAddress()) == devices_.end());
 
   devices_[device_chromeos->GetAddress()] = device_chromeos;
 
   FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,
                     DeviceAdded(this, device_chromeos));
 }
 
 void BluetoothAdapterChromeOS::DeviceRemoved(
     const dbus::ObjectPath& object_path) {
+  DCHECK(IsPresent());
   for (DevicesMap::iterator iter = devices_.begin();
        iter != devices_.end(); ++iter) {
     BluetoothDeviceChromeOS* device_chromeos =
         static_cast<BluetoothDeviceChromeOS*>(iter->second);
     if (device_chromeos->object_path() == object_path) {
       devices_.erase(iter);
 
       FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,
                         DeviceRemoved(this, device_chromeos));
       delete device_chromeos;
       return;
     }
   }
 }
 
 void BluetoothAdapterChromeOS::DevicePropertyChanged(
     const dbus::ObjectPath& object_path,
     const std::string& property_name) {
+  DCHECK(IsPresent());
   BluetoothDeviceChromeOS* device_chromeos = GetDeviceWithPath(object_path);
   if (!device_chromeos)
     return;
 
   BluetoothDeviceClient::Properties* properties =
       DBusThreadManager::Get()->GetBluetoothDeviceClient()->
           GetProperties(object_path);
 
   if (property_name == properties->bluetooth_class.name() ||
       property_name == properties->address.name() ||
@@ skipping 28 matching lines @@
         ++count;
     }
 
     UMA_HISTOGRAM_COUNTS_100("Bluetooth.ConnectedDeviceCount", count);
   }
 }
 
 void BluetoothAdapterChromeOS::InputPropertyChanged(
     const dbus::ObjectPath& object_path,
     const std::string& property_name) {
+  DCHECK(IsPresent());
   BluetoothDeviceChromeOS* device_chromeos = GetDeviceWithPath(object_path);
   if (!device_chromeos)
     return;
 
   BluetoothInputClient::Properties* properties =
       DBusThreadManager::Get()->GetBluetoothInputClient()->
           GetProperties(object_path);
 
   // Properties structure can be removed, which triggers a change in the
   // BluetoothDevice::IsConnectable() property, as does a change in the
   // actual reconnect_mode property.
   if (!properties ||
       property_name == properties->reconnect_mode.name())
     NotifyDeviceChanged(device_chromeos);
 }
 
 void BluetoothAdapterChromeOS::Released() {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << "Release";
 
   // Called after we unregister the pairing agent, e.g. when changing I/O
   // capabilities. Nothing much to be done right now.
 }
 
 void BluetoothAdapterChromeOS::RequestPinCode(
     const dbus::ObjectPath& device_path,
     const PinCodeCallback& callback) {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << device_path.value() << ": RequestPinCode";
 
   BluetoothPairingChromeOS* pairing = GetPairing(device_path);
   if (!pairing) {
     callback.Run(REJECTED, "");
     return;
   }
 
   pairing->RequestPinCode(callback);
 }
 
 void BluetoothAdapterChromeOS::DisplayPinCode(
     const dbus::ObjectPath& device_path,
     const std::string& pincode) {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << device_path.value() << ": DisplayPinCode: " << pincode;
 
   BluetoothPairingChromeOS* pairing = GetPairing(device_path);
   if (!pairing)
     return;
 
   pairing->DisplayPinCode(pincode);
 }
 
 void BluetoothAdapterChromeOS::RequestPasskey(
     const dbus::ObjectPath& device_path,
     const PasskeyCallback& callback) {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << device_path.value() << ": RequestPasskey";
 
   BluetoothPairingChromeOS* pairing = GetPairing(device_path);
   if (!pairing) {
     callback.Run(REJECTED, 0);
     return;
   }
 
   pairing->RequestPasskey(callback);
 }
 
 void BluetoothAdapterChromeOS::DisplayPasskey(
     const dbus::ObjectPath& device_path,
     uint32 passkey,
     uint16 entered) {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << device_path.value() << ": DisplayPasskey: " << passkey
           << " (" << entered << " entered)";
 
   BluetoothPairingChromeOS* pairing = GetPairing(device_path);
   if (!pairing)
     return;
 
   if (entered == 0)
     pairing->DisplayPasskey(passkey);
 
   pairing->KeysEntered(entered);
 }
 
 void BluetoothAdapterChromeOS::RequestConfirmation(
     const dbus::ObjectPath& device_path,
     uint32 passkey,
     const ConfirmationCallback& callback) {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << device_path.value() << ": RequestConfirmation: " << passkey;
 
   BluetoothPairingChromeOS* pairing = GetPairing(device_path);
   if (!pairing) {
     callback.Run(REJECTED);
     return;
   }
 
   pairing->RequestConfirmation(passkey, callback);
 }
 
 void BluetoothAdapterChromeOS::RequestAuthorization(
     const dbus::ObjectPath& device_path,
     const ConfirmationCallback& callback) {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << device_path.value() << ": RequestAuthorization";
 
   BluetoothPairingChromeOS* pairing = GetPairing(device_path);
   if (!pairing) {
     callback.Run(REJECTED);
     return;
   }
 
   pairing->RequestAuthorization(callback);
 }
 
 void BluetoothAdapterChromeOS::AuthorizeService(
     const dbus::ObjectPath& device_path,
     const std::string& uuid,
     const ConfirmationCallback& callback) {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << device_path.value() << ": AuthorizeService: " << uuid;
 
   BluetoothDeviceChromeOS* device_chromeos = GetDeviceWithPath(device_path);
   if (!device_chromeos) {
     callback.Run(CANCELLED);
     return;
   }
 
   // We always set paired devices to Trusted, so the only reason that this
   // method call would ever be called is in the case of a race condition where
   // our "Set('Trusted', true)" method call is still pending in the Bluetooth
   // daemon because it's busy handling the incoming connection.
   if (device_chromeos->IsPaired()) {
     callback.Run(SUCCESS);
     return;
   }
 
   // TODO(keybuk): reject service authorizations when not paired, determine
   // whether this is acceptable long-term.
   LOG(WARNING) << "Rejecting service connection from unpaired device "
                << device_chromeos->GetAddress() << " for UUID " << uuid;
   callback.Run(REJECTED);
 }
 
 void BluetoothAdapterChromeOS::Cancel() {
+  DCHECK(IsPresent());
   DCHECK(agent_.get());
   VLOG(1) << "Cancel";
 }
 
 void BluetoothAdapterChromeOS::OnRegisterAgent() {
+  DCHECK(IsPresent());
   VLOG(1) << "Pairing agent registered, requesting to be made default";
 
   DBusThreadManager::Get()->GetBluetoothAgentManagerClient()->
       RequestDefaultAgent(
           dbus::ObjectPath(kAgentPath),
           base::Bind(&BluetoothAdapterChromeOS::OnRequestDefaultAgent,
                      weak_ptr_factory_.GetWeakPtr()),
           base::Bind(&BluetoothAdapterChromeOS::OnRequestDefaultAgentError,
                      weak_ptr_factory_.GetWeakPtr()));
 }
 
 void BluetoothAdapterChromeOS::OnRegisterAgentError(
     const std::string& error_name,
     const std::string& error_message) {
+  DCHECK(IsPresent());
   // Our agent being already registered isn't an error.
   if (error_name == bluetooth_agent_manager::kErrorAlreadyExists)
     return;
 
   LOG(WARNING) << ": Failed to register pairing agent: "
                << error_name << ": " << error_message;
 }
 
 void BluetoothAdapterChromeOS::OnRequestDefaultAgent() {
+  DCHECK(IsPresent());
   VLOG(1) << "Pairing agent now default";
 }
 
 void BluetoothAdapterChromeOS::OnRequestDefaultAgentError(
     const std::string& error_name,
     const std::string& error_message) {
+  DCHECK(IsPresent());
   LOG(WARNING) << ": Failed to make pairing agent default: "
                << error_name << ": " << error_message;
 }
 
 BluetoothDeviceChromeOS*
 BluetoothAdapterChromeOS::GetDeviceWithPath(
     const dbus::ObjectPath& object_path) {
-  for (DevicesMap::iterator iter = devices_.begin();
-       iter != devices_.end(); ++iter) {
+  if (!IsPresent())
+    return NULL;
+
+  for (DevicesMap::iterator iter = devices_.begin(); iter != devices_.end();
+       ++iter) {
     BluetoothDeviceChromeOS* device_chromeos =
         static_cast<BluetoothDeviceChromeOS*>(iter->second);
     if (device_chromeos->object_path() == object_path)
       return device_chromeos;
   }
 
   return NULL;
 }
 
 BluetoothPairingChromeOS* BluetoothAdapterChromeOS::GetPairing(
     const dbus::ObjectPath& object_path) {
+  DCHECK(IsPresent());
   BluetoothDeviceChromeOS* device_chromeos = GetDeviceWithPath(object_path);
   if (!device_chromeos) {
     LOG(WARNING) << "Pairing Agent request for unknown device: "
                  << object_path.value();
     return NULL;
   }
 
   BluetoothPairingChromeOS* pairing = device_chromeos->GetPairing();
   if (pairing)
     return pairing;
 
   // The device doesn't have its own pairing context, so this is an incoming
   // pairing request that should use our best default delegate (if we have one).
   BluetoothDevice::PairingDelegate* pairing_delegate = DefaultPairingDelegate();
   if (!pairing_delegate)
     return NULL;
 
   return device_chromeos->BeginPairing(pairing_delegate);
 }
 
 void BluetoothAdapterChromeOS::SetAdapter(const dbus::ObjectPath& object_path) {
   DCHECK(!IsPresent());
+  DCHECK(!dbus_is_shutdown_);
   object_path_ = object_path;
 
   VLOG(1) << object_path_.value() << ": using adapter.";
 
   VLOG(1) << "Registering pairing agent";
   DBusThreadManager::Get()->GetBluetoothAgentManagerClient()->
       RegisterAgent(
           dbus::ObjectPath(kAgentPath),
           bluetooth_agent_manager::kKeyboardDisplayCapability,
           base::Bind(&BluetoothAdapterChromeOS::OnRegisterAgent,
@@ skipping 20 matching lines @@
       DBusThreadManager::Get()->GetBluetoothDeviceClient()->
           GetDevicesForAdapter(object_path_);
 
   for (std::vector<dbus::ObjectPath>::iterator iter = device_paths.begin();
        iter != device_paths.end(); ++iter) {
     DeviceAdded(*iter);
   }
 }
 
 void BluetoothAdapterChromeOS::SetDefaultAdapterName() {
+  DCHECK(IsPresent());
   std::string board = base::SysInfo::GetLsbReleaseBoard();
   std::string alias;
   if (board.substr(0, 6) == "stumpy") {
     alias = "Chromebox";
   } else if (board.substr(0, 4) == "link") {
     alias = "Chromebook Pixel";
   } else {
     alias = "Chromebook";
   }
 
@@ skipping 178 matching lines @@
 
   FOR_EACH_OBSERVER(BluetoothAdapter::Observer,
                     observers_,
                     GattDescriptorValueChanged(this, descriptor, value));
 }
 
 void BluetoothAdapterChromeOS::OnSetDiscoverable(
     const base::Closure& callback,
     const ErrorCallback& error_callback,
     bool success) {
+  DCHECK(IsPresent());
   // Set the discoverable_timeout property to zero so the adapter remains
   // discoverable forever.
   DBusThreadManager::Get()->GetBluetoothAdapterClient()->
       GetProperties(object_path_)->discoverable_timeout.Set(
           0,
           base::Bind(&BluetoothAdapterChromeOS::OnPropertyChangeCompleted,
                      weak_ptr_factory_.GetWeakPtr(),
                      callback,
                      error_callback));
 }
 
 void BluetoothAdapterChromeOS::OnPropertyChangeCompleted(
     const base::Closure& callback,
     const ErrorCallback& error_callback,
     bool success) {
+  DCHECK(IsPresent());
   if (success)
     callback.Run();
   else
     error_callback.Run();
 }
 
 void BluetoothAdapterChromeOS::AddDiscoverySession(
     const base::Closure& callback,
     const ErrorCallback& error_callback) {
+  if (!IsPresent()) {
+    error_callback.Run();
+    return;
+  }
   VLOG(1) << __func__;
   if (discovery_request_pending_) {
     // The pending request is either to stop a previous session or to start a
     // new one. Either way, queue this one.
     DCHECK(num_discovery_sessions_ == 1 || num_discovery_sessions_ == 0);
     VLOG(1) << "Pending request to start/stop device discovery. Queueing "
             << "request to start a new discovery session.";
     discovery_request_queue_.push(std::make_pair(callback, error_callback));
     return;
   }
@@ skipping 20 matching lines @@
                      callback),
           base::Bind(&BluetoothAdapterChromeOS::OnStartDiscoveryError,
                      weak_ptr_factory_.GetWeakPtr(),
                      callback,
                      error_callback));
 }
 
 void BluetoothAdapterChromeOS::RemoveDiscoverySession(
     const base::Closure& callback,
     const ErrorCallback& error_callback) {
+  DCHECK(IsPresent());
   VLOG(1) << __func__;
   // There are active sessions other than the one currently being removed.
   if (num_discovery_sessions_ > 1) {
     DCHECK(IsDiscovering());
     DCHECK(!discovery_request_pending_);
     num_discovery_sessions_--;
     callback.Run();
     return;
   }
 
@@ skipping 24 matching lines @@
           object_path_,
           base::Bind(&BluetoothAdapterChromeOS::OnStopDiscovery,
                      weak_ptr_factory_.GetWeakPtr(),
                      callback),
           base::Bind(&BluetoothAdapterChromeOS::OnStopDiscoveryError,
                      weak_ptr_factory_.GetWeakPtr(),
                      error_callback));
 }
 
 void BluetoothAdapterChromeOS::OnStartDiscovery(const base::Closure& callback) {
+  DCHECK(IsPresent());
   // Report success on the original request and increment the count.
   VLOG(1) << __func__;
   DCHECK(discovery_request_pending_);
   DCHECK(num_discovery_sessions_ == 0);
   discovery_request_pending_ = false;
   num_discovery_sessions_++;
   callback.Run();
 
   // Try to add a new discovery session for each queued request.
   ProcessQueuedDiscoveryRequests();
 }
 
 void BluetoothAdapterChromeOS::OnStartDiscoveryError(
     const base::Closure& callback,
     const ErrorCallback& error_callback,
     const std::string& error_name,
     const std::string& error_message) {
+  DCHECK(IsPresent());
   LOG(WARNING) << object_path_.value() << ": Failed to start discovery: "
                << error_name << ": " << error_message;
 
   // Failed to start discovery. This can only happen if the count is at 0.
   DCHECK(num_discovery_sessions_ == 0);
   DCHECK(discovery_request_pending_);
   discovery_request_pending_ = false;
 
   // Discovery request may fail if discovery was previously initiated by Chrome,
   // but the session were invalidated due to the discovery state unexpectedly
   // changing to false and then back to true. In this case, report success.
   if (error_name == bluetooth_device::kErrorInProgress && IsDiscovering()) {
     VLOG(1) << "Discovery previously initiated. Reporting success.";
     num_discovery_sessions_++;
     callback.Run();
   } else {
     error_callback.Run();
   }
 
   // Try to add a new discovery session for each queued request.
   ProcessQueuedDiscoveryRequests();
 }
 
 void BluetoothAdapterChromeOS::OnStopDiscovery(const base::Closure& callback) {
+  DCHECK(IsPresent());
   // Report success on the original request and decrement the count.
   VLOG(1) << __func__;
   DCHECK(discovery_request_pending_);
   DCHECK(num_discovery_sessions_ == 1);
   discovery_request_pending_ = false;
   num_discovery_sessions_--;
   callback.Run();
 
   // Try to add a new discovery session for each queued request.
   ProcessQueuedDiscoveryRequests();
 }
 
 void BluetoothAdapterChromeOS::OnStopDiscoveryError(
     const ErrorCallback& error_callback,
     const std::string& error_name,
     const std::string& error_message) {
+  DCHECK(IsPresent());
   LOG(WARNING) << object_path_.value() << ": Failed to stop discovery: "
                << error_name << ": " << error_message;
 
   // Failed to stop discovery. This can only happen if the count is at 1.
   DCHECK(discovery_request_pending_);
   DCHECK(num_discovery_sessions_ == 1);
   discovery_request_pending_ = false;
   error_callback.Run();
 
   // Try to add a new discovery session for each queued request.
   ProcessQueuedDiscoveryRequests();
 }
 
 void BluetoothAdapterChromeOS::ProcessQueuedDiscoveryRequests() {
   while (!discovery_request_queue_.empty()) {
     VLOG(1) << "Process queued discovery request.";
     DiscoveryCallbackPair callbacks = discovery_request_queue_.front();
     discovery_request_queue_.pop();
     AddDiscoverySession(callbacks.first, callbacks.second);
 
     // If the queued request resulted in a pending call, then let it
     // asynchonously process the remaining queued requests once the pending
     // call returns.
     if (discovery_request_pending_)
       return;
   }
 }
 
 }  // namespace chromeos