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

device/bluetooth/bluetooth_adapter.h

 // Copyright (c) 2012 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.
 
 #ifndef DEVICE_BLUETOOTH_BLUETOOTH_ADAPTER_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_ADAPTER_H_
 
 #include <list>
 #include <map>
 #include <set>
@@ skipping 197 matching lines @@
   // Shutdown the adapter: tear down and clean up all objects owned by
   // BluetoothAdapter. After this call, the BluetoothAdapter will behave as if
   // no Bluetooth controller exists in the local system. |IsPresent| will return
   // false.
   virtual void Shutdown();
 #endif
 
   // Adds and removes observers for events on this bluetooth adapter. If
   // monitoring multiple adapters, check the |adapter| parameter of observer
   // methods to determine which adapter is issuing the event.
-  virtual void AddObserver(BluetoothAdapter::Observer* observer) = 0;
-  virtual void RemoveObserver(
-      BluetoothAdapter::Observer* observer) = 0;
+  virtual void AddObserver(BluetoothAdapter::Observer* observer);
+  virtual void RemoveObserver(BluetoothAdapter::Observer* observer);
 
   // The address of this adapter. The address format is "XX:XX:XX:XX:XX:XX",
   // where each XX is a hexadecimal number.
   virtual std::string GetAddress() const = 0;
 
   // The name of the adapter.
   virtual std::string GetName() const = 0;
 
   // Set the human-readable name of the adapter to |name|. On success,
   // |callback| will be called. On failure, |error_callback| will be called.
@@ skipping 216 matching lines @@
   // BluetoothAdapter in the event that the adapter unexpectedly stops
   // discovering. This should be called by all platform implementations.
   void MarkDiscoverySessionsAsInactive();
 
   // Removes |discovery_session| from |discovery_sessions_|, if its in there.
   // Called by DiscoverySession when an instance is destroyed or becomes
   // inactive.
   void DiscoverySessionBecameInactive(
       BluetoothDiscoverySession* discovery_session);
 
+  // Observers of BluetoothAdapter, notified from implementation subclasses.
+  ObserverList<device::BluetoothAdapter::Observer> observers_;
+
   // Devices paired with, connected to, discovered by, or visible to the
   // adapter. The key is the Bluetooth address of the device and the value is
   // the BluetoothDevice object whose lifetime is managed by the adapter
   // instance.
   DevicesMap devices_;
 
   // Default pairing delegates registered with the adapter.
   std::list<PairingDelegatePair> pairing_delegates_;
 
  private:
@@ skipping 19 matching lines @@
 // Trait for RefCountedThreadSafe that deletes BluetoothAdapter.
 struct BluetoothAdapterDeleter {
   static void Destruct(const BluetoothAdapter* adapter) {
     adapter->DeleteOnCorrectThread();
   }
 };
 
 }  // namespace device
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_ADAPTER_H_