DIAL extension API skeleton.

chrome/browser/extensions/api/dial/dial_registry.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 CHROME_BROWSER_EXTENSIONS_API_DIAL_DIAL_REGISTRY_H_
+#define CHROME_BROWSER_EXTENSIONS_API_DIAL_DIAL_REGISTRY_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "chrome/browser/extensions/api/dial/dial_device_data.h"
+
+namespace extensions {
+
+// Keeps track of devices that have responded to discovery requests and notifies
+// the observer with the set of active devices has changed.  The registry's
+// observer (i.e., the Dial API) owns the registry instance.
+class DialRegistry {
+ public:
+  typedef std::vector<DialDeviceData> DeviceList;
+
+  class Observer {
+   public:
+    // Invoked on the IO thread by the DialRegistry during a device event (new
+    // device discovered or an update triggered by dial.discoverNow).
+    virtual void OnDialDeviceEvent(const DeviceList& devices) = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  // Create the DIAL registry and pass a reference to allow it to notify on
+  // DIAL device events.
+  explicit DialRegistry(Observer *dial_api);
+  virtual ~DialRegistry();
+
+  // Called by the DIAL API when event listeners are added or removed. The dial
+  // service is started after the first listener is added and stopped after the
+  // last listener is removed.
+  void OnListenerAdded();
+  void OnListenerRemoved();
+
+  // Called by the DIAL API to try to kickoff a discovery if there is not one
+  // already active.
+  bool DiscoverNow();
+
+ private:
+  // The current number of event listeners attached to this registry.
+  int num_listeners_;
+
+  // Whether discovering is currently active.
+  bool discovering_;
+
+  // Interface from which the DIAL API is notified of DIAL device events. the
+  // DIAL API owns this DIAL registry.
+  Observer* dial_api_;
+
+  // Thread checker.
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(DialRegistry);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_DIAL_DIAL_REGISTRY_H_