Implement BluetoothTestBlueZ and enable some LE tests.

device/bluetooth/bluetooth_adapter_bluez.h

Index: device/bluetooth/bluetooth_adapter_bluez.h
diff --git a/device/bluetooth/bluetooth_adapter_bluez.h b/device/bluetooth/bluetooth_adapter_bluez.h
index 6fb20db7b5a10d6dde01a3304ccf680d37b474ac..c5758fafadf03b89517f020cd981a10b1f700429 100644
--- a/device/bluetooth/bluetooth_adapter_bluez.h
+++ b/device/bluetooth/bluetooth_adapter_bluez.h
@@ -35,6 +35,7 @@ class SequencedTaskRunner;
 
 namespace device {
 class BluetoothSocketThread;
+class BluetoothTestBlueZ;
 }  // namespace device
 
 namespace bluez {
@@ -162,6 +163,7 @@ class DEVICE_BLUETOOTH_EXPORT BluetoothAdapterBlueZ
   friend class BluetoothBlueZTest_Shutdown_OnStartDiscoveryError_Test;
   friend class BluetoothBlueZTest_Shutdown_OnStopDiscovery_Test;
   friend class BluetoothBlueZTest_Shutdown_OnStopDiscoveryError_Test;
+  friend class device::BluetoothTestBlueZ;
 
   // typedef for callback parameters that are passed to AddDiscoverySession
   // and RemoveDiscoverySession. This is used to queue incoming requests while