bluetooth: Refactor (Add|Remove)Observer impls into BluetoothAdapter.

device/bluetooth/bluetooth_adapter_mac.mm

Index: device/bluetooth/bluetooth_adapter_mac.mm
diff --git a/device/bluetooth/bluetooth_adapter_mac.mm b/device/bluetooth/bluetooth_adapter_mac.mm
index 7c04a433c419cdf6d69e6adf0d12b2065bb26d6d..c2e77eeef55da4f30ccc13d6aed1c694b5a56732 100644
--- a/device/bluetooth/bluetooth_adapter_mac.mm
+++ b/device/bluetooth/bluetooth_adapter_mac.mm
@@ -64,16 +64,6 @@ BluetoothAdapterMac::BluetoothAdapterMac()
 BluetoothAdapterMac::~BluetoothAdapterMac() {
 }
 
-void BluetoothAdapterMac::AddObserver(BluetoothAdapter::Observer* observer) {
-  DCHECK(observer);
-  observers_.AddObserver(observer);
-}
-
-void BluetoothAdapterMac::RemoveObserver(BluetoothAdapter::Observer* observer) {
-  DCHECK(observer);
-  observers_.RemoveObserver(observer);
-}
-
 std::string BluetoothAdapterMac::GetAddress() const {
   return address_;
 }