bluetooth: Shutdown BluetoothAdapter before DBus on ChromeOS.

device/bluetooth/bluetooth_adapter_chromeos.h

Index: device/bluetooth/bluetooth_adapter_chromeos.h
diff --git a/device/bluetooth/bluetooth_adapter_chromeos.h b/device/bluetooth/bluetooth_adapter_chromeos.h
index 0bcd6f741fe3e52368fa1ce2f421971f3a3d8057..eb2e3dbfa8e495025faaa03d5150df17f0c7621c 100644
--- a/device/bluetooth/bluetooth_adapter_chromeos.h
+++ b/device/bluetooth/bluetooth_adapter_chromeos.h
@@ -43,6 +43,12 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterChromeOS
  public:
   static base::WeakPtr<BluetoothAdapter> CreateAdapter();
 
+  // Shutdown the adapter: tear down and clean up all objects owned by
+  // BluetoothAdapter. After this call, the BluetoothAdapter will behave as if
+  // no Bluetooth controller exists in the local system. |IsPresent| will return
+  // false. No futher use of DBusThreadManager will be made.
+  void OnDBusThreadManagerShutdown();
+
   // BluetoothAdapter:
   void DeleteOnCorrectThread() const override;
   virtual void AddObserver(
@@ -241,6 +247,9 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterChromeOS
   // ended (with either success or failure).
   void ProcessQueuedDiscoveryRequests();
 
+  // Set in |OnDBusThreadManagerShutdown()|, makes IsPresent()| return false.
+  bool dbus_is_shutdown_;
+
   // Number of discovery sessions that have been added.
   int num_discovery_sessions_;