Initial chrome.mdns API.

chrome/browser/extensions/api/mdns/mdns_api.h

+// Copyright (c) 2013 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_MDNS_MDNS_API_H_
+#define CHROME_BROWSER_EXTENSIONS_API_MDNS_MDNS_API_H_
+
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/gtest_prod_util.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "chrome/browser/extensions/api/mdns/nsd_registry.h"
+#include "chrome/browser/extensions/event_router.h"
+#include "components/browser_context_keyed_service/browser_context_keyed_service.h"
+
+namespace extensions {
+
+// MDnsAPI is instantiated with the profile and will listen for extensions that
+// register listeners for the MDNS extension API. It will use an NSD registry

[mark a. foltz, 2013/08/30 01:35:52]

s/MDNS/chrome.mdns/

[mark a. foltz, 2013/08/30 01:35:52]

You might explain what 'NSD' means in this context.

[mark a. foltz, 2013/08/30 01:35:52]

extensions that register DNS-SD service types with the ... manifest key.

[justinlin, 2013/09/03 21:21:56]

Done.

[justinlin, 2013/09/03 21:21:56]

Not addressing this for now since we might use filters instead.

[justinlin, 2013/09/03 21:21:56]

Done.

+// class to start discovery and observe new service events to dispatch them to

[mark a. foltz, 2013/08/30 01:35:52]

... to start the mDNS listener process (if necessary) and ...

[justinlin, 2013/09/03 21:21:56]

Done.

+// registered extensions.
+class MDnsAPI : public BrowserContextKeyedService,
+                public EventRouter::Observer,
+                public NsdRegistry::NsdObserver {
+ public:
+  explicit MDnsAPI(Profile* profile);
+  virtual ~MDnsAPI();
+
+  // Used to mock out the NsdRegistry for testing.
+  void SetNsdRegistryForTesting(NsdRegistry* registry);

[mark a. foltz, 2013/08/30 01:35:52]

Since nsd_registry() is virtual would it be easier to override it in tests?

[justinlin, 2013/09/03 21:21:56]

The problem is that in browser_tests, I can't see to find a way to do anything
before this class is created since it's initialized earlier than the test hooks,
so I have to override the registry in this function.

+
+ protected:
+  // Retrieve an instance to the registry. Lazily create it if needed.
+  virtual NsdRegistry* nsd_registry();
+
+ private:
+  // Mapping from MDNS service types to currently listening extensions.
+  typedef std::map<std::string, std::set<std::string> >
+      ServiceTypeToExtensionsMap;
+
+  // EventRouter::Observer:
+  virtual void OnListenerAdded(const EventListenerInfo& details) OVERRIDE;
+  virtual void OnListenerRemoved(const EventListenerInfo& details) OVERRIDE;
+
+  // NsdRegistry::Observer
+  virtual void OnMDnsEvent(
+      const std::string& service_type,
+      const NsdRegistry::NsdServiceList& services) OVERRIDE;
+
+
+  base::ThreadChecker thread_checker_;

[mark a. foltz, 2013/08/30 01:35:52]

Add a comment that this API is normally only called from the UI thread.

[justinlin, 2013/09/03 21:21:56]

Done.

+  Profile* const profile_;
+  scoped_ptr<NsdRegistry> nsd_registry_;

[mark a. foltz, 2013/08/30 01:35:52]

Add a comment?  Note that it is created lazily and lifetime tied to this object?

[justinlin, 2013/09/03 21:21:56]

Done.

+  ServiceTypeToExtensionsMap service_type_to_extensions_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(MDnsAPI);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_MDNS_MDNS_API_H_