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

device/bluetooth/bluetooth_adapter_win.cc

Index: device/bluetooth/bluetooth_adapter_win.cc
diff --git a/device/bluetooth/bluetooth_adapter_win.cc b/device/bluetooth/bluetooth_adapter_win.cc
index a9fc200348d1259ecc2056fb263cc11801c48f57..20cd8971e12a5b1c294863fa8a40b51a2d700acb 100644
--- a/device/bluetooth/bluetooth_adapter_win.cc
+++ b/device/bluetooth/bluetooth_adapter_win.cc
@@ -53,16 +53,6 @@ BluetoothAdapterWin::~BluetoothAdapterWin() {
   }
 }
 
-void BluetoothAdapterWin::AddObserver(BluetoothAdapter::Observer* observer) {
-  DCHECK(observer);
-  observers_.AddObserver(observer);
-}
-
-void BluetoothAdapterWin::RemoveObserver(BluetoothAdapter::Observer* observer) {
-  DCHECK(observer);
-  observers_.RemoveObserver(observer);
-}
-
 std::string BluetoothAdapterWin::GetAddress() const {
   return address_;
 }