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

device/bluetooth/bluetooth_adapter_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/bind.h"
 #include "base/memory/ref_counted.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 #include "device/bluetooth/bluetooth_device.h"
 #include "device/bluetooth/bluetooth_discovery_session.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using device::BluetoothAdapter;
 using device::BluetoothDevice;
 
 namespace device {
 
 class TestBluetoothAdapter : public BluetoothAdapter {
  public:
   TestBluetoothAdapter() {
   }
 
-  void AddObserver(BluetoothAdapter::Observer* observer) override {}
-
-  void RemoveObserver(BluetoothAdapter::Observer* observer) override {}
-
   std::string GetAddress() const override { return ""; }
 
   std::string GetName() const override { return ""; }
 
   void SetName(const std::string& name,
                const base::Closure& callback,
                const ErrorCallback& error_callback) override {}
 
   bool IsInitialized() const override { return false; }
 
@@ skipping 353 matching lines @@
               resulting_uuids.end());
 
   resulting_filter = adapter->GetMergedDiscoveryFilterMasked(df);
   EXPECT_EQ(BluetoothDiscoveryFilter::Transport::TRANSPORT_DUAL,
             resulting_filter->GetTransport());
 
   adapter->CleanupSessions();
 }
 
 }  // namespace device