Fix //third_party/cec to not disable -Wunused-function.

device/bluetooth/bluetooth_device_unittest.cc

Index: device/bluetooth/bluetooth_device_unittest.cc
diff --git a/device/bluetooth/bluetooth_device_unittest.cc b/device/bluetooth/bluetooth_device_unittest.cc
index 9433fda99ef8071763ef0334f2aa22e896eafcfb..8d10181907374bef46b4945fe43f02b0889849fe 100644
--- a/device/bluetooth/bluetooth_device_unittest.cc
+++ b/device/bluetooth/bluetooth_device_unittest.cc
@@ -27,6 +27,8 @@
 
 namespace device {
 
+#if defined(OS_ANDROID) || defined(OS_MACOSX)
+
 namespace {
 
 int8_t ToInt8(BluetoothTest::TestRSSI rssi) {
@@ -39,6 +41,8 @@ int8_t ToInt8(BluetoothTest::TestTxPower tx_power) {
 
 }  // namespace
 
+#endif
+
 using UUIDSet = BluetoothDevice::UUIDSet;
 using ServiceDataMap = BluetoothDevice::ServiceDataMap;