bluetooth: Add adapter to BluetoothDevice

device/bluetooth/bluetooth_device_chromeos.h

Index: device/bluetooth/bluetooth_device_chromeos.h
diff --git a/device/bluetooth/bluetooth_device_chromeos.h b/device/bluetooth/bluetooth_device_chromeos.h
index f937be7465ed94a91fd07e9d5c46a58c78ffe969..f8846cdb37e3fbb012da23aa0a38a4514adeb514 100644
--- a/device/bluetooth/bluetooth_device_chromeos.h
+++ b/device/bluetooth/bluetooth_device_chromeos.h
@@ -96,7 +96,7 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDeviceChromeOS
   const dbus::ObjectPath& object_path() const { return object_path_; }
 
   // Returns the adapter which owns this device instance.
-  BluetoothAdapterChromeOS* adapter() const { return adapter_; }
+  BluetoothAdapterChromeOS* adapter() const;
 
  protected:
   // BluetoothDevice override
@@ -173,9 +173,6 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothDeviceChromeOS
                      const std::string& error_name,
                      const std::string& error_message);
 
-  // The adapter that owns this device instance.
-  BluetoothAdapterChromeOS* adapter_;
-
   // The dbus object path of the device object.
   dbus::ObjectPath object_path_;