Migrate chrome.bluetooth API backend to use device::BluetoothDiscoverySession.

device/bluetooth/bluetooth_discovery_session.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 "device/bluetooth/bluetooth_discovery_session.h"
 
 #include "base/bind.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 
 namespace device {
 
-BluetoothDiscoverySession::BluetoothDiscoverySession(BluetoothAdapter* adapter)
+BluetoothDiscoverySession::BluetoothDiscoverySession(
+    scoped_refptr<BluetoothAdapter> adapter)
     : active_(true),
       adapter_(adapter),
       weak_ptr_factory_(this) {
 }
 
 BluetoothDiscoverySession::~BluetoothDiscoverySession() {
   Stop(base::Bind(&base::DoNothing), base::Bind(&base::DoNothing));
+  DCHECK(adapter_.get());
   adapter_->DiscoverySessionDestroyed(this);
 }
 
 void BluetoothDiscoverySession::Stop(
     const base::Closure& callback,
     const ErrorCallback& error_callback) {
   if (!active_) {
-    LOG(ERROR) << "Discovery session not active. Cannot stop.";
+    LOG(WARNING) << "Discovery session not active. Cannot stop.";
     error_callback.Run();
     return;
   }
   VLOG(1) << "Stopping device discovery session.";
+  DCHECK(adapter_.get());
   adapter_->RemoveDiscoverySession(
       base::Bind(&BluetoothDiscoverySession::OnStop,
                  weak_ptr_factory_.GetWeakPtr(),
                  callback),
       error_callback);
 }
 
 void BluetoothDiscoverySession::OnStop(const base::Closure& callback) {
   active_ = false;
   callback.Run();
 }
 
 void BluetoothDiscoverySession::MarkAsInactive() {
   active_ = false;
 }
 
 }  // namespace device