Initial chrome.mdns API.

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

+// 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.
+
+#include "chrome/browser/extensions/api/mdns/mdns_api.h"
+
+#include "chrome/browser/extensions/api/mdns/mdns_api_factory.h"
+#include "chrome/browser/extensions/extension_service.h"
+#include "chrome/browser/extensions/extension_system.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/common/extensions/api/mdns.h"
+#include "chrome/common/extensions/api/mdns/mdns_manifest_handler.h"
+#include "extensions/common/manifest_constants.h"
+
+namespace extensions {
+
+namespace mdns = api::mdns;
+
+namespace {
+
+// Retrieves the list of service types that are declared in the extension's
+// manifest file.
+const std::vector<std::string> GetServiceTypesForExtension(

[Matt Perry, 2013/08/30 00:43:29]

you can return a reference here

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

Done. Have to use a lazy instance to return if extension is not found, but not a
big deal since it should not be hit usually.

+    Profile* profile, std::string extension_id) {

[Matt Perry, 2013/08/30 00:43:29]

pass strings by const ref

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

Done.

+  const extensions::Extension* extension = ExtensionSystem::Get(profile)->
+      extension_service()->GetExtensionById(extension_id, false);
+  if (!extension) {
+    NOTREACHED();

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

Include a message

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

Done.

+    return std::vector<std::string>();
+  }
+  const MDnsInfo& info = MDnsInfo::GetMDnsInfo(extension);

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

Combine this with the return statement?

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

Done.

+  return info.service_types;
+}
+
+}  // namespace
+
+MDnsAPI::MDnsAPI(Profile* profile) : profile_(profile) {
+  DCHECK(profile_);
+  ExtensionSystem::Get(profile)->event_router()->RegisterObserver(
+      this, mdns::OnServiceList::kEventName);
+}
+
+MDnsAPI::~MDnsAPI() {
+  if (nsd_registry_.get()) {
+    nsd_registry_->RemoveObserver(this);
+  }
+}
+
+void MDnsAPI::SetNsdRegistryForTesting(NsdRegistry* nsd_registry) {

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

Make clear (in a comment or the .h) that the MDnsAPI takes ownership of the
argument.  Maybe take a scoped_ptr<> and release() it?

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

Done.

+  nsd_registry_.reset(nsd_registry);
+}
+
+NsdRegistry* MDnsAPI::nsd_registry() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (!nsd_registry_.get()) {
+    nsd_registry_.reset(new extensions::NsdRegistry());
+    nsd_registry_->AddObserver(this);
+  }
+  return nsd_registry_.get();
+}
+
+void MDnsAPI::OnListenerAdded(const EventListenerInfo& details) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  const std::string& extension_id = details.extension_id;
+  const std::vector<std::string>& service_types =
+      GetServiceTypesForExtension(profile_, extension_id);
+  for (std::vector<std::string>::const_iterator it = service_types.begin();
+       it != service_types.end(); ++it) {
+    // Start watchers for all the service types this extension has declared.
+    const std::string& service_type = *it;
+    DVLOG(1) << "Registered watcher for service type \"" << service_type
+             << "\" for extension \"" << extension_id << "\"";
+    service_type_to_extensions_map_[service_type].insert(extension_id);

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

Check return value?
I guess we don't care about duplicate insertions?

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

Added DCHECK, we should never get duplicate insertions I think. I only see this
event once per extension no matter how many listeners are added.

+    nsd_registry()->RegisterMDnsListener(service_type);
+  }
+}
+
+void MDnsAPI::OnListenerRemoved(const EventListenerInfo& details) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  const std::string& extension_id = details.extension_id;
+  for (ServiceTypeToExtensionsMap::iterator it =
+       service_type_to_extensions_map_.begin();
+       it != service_type_to_extensions_map_.end(); it++) {
+    const std::string& service_type = it->first;
+    std::set<std::string>& extensions = it->second;
+    if (extensions.erase(extension_id)) {
+      if (!extensions.size()) {

[Matt Perry, 2013/08/30 00:43:29]

nit: size is not a boolean. use either size() == 0 or empty()

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

Done.

+        DVLOG(1) << "Removed all watchers for service type \"" << service_type
+                 << "\"";
+        nsd_registry()->UnregisterMDnsListener(service_type);
+        service_type_to_extensions_map_.erase(service_type);

[Matt Perry, 2013/08/30 00:43:29]

This will invalidate your iterator. You should do
  service_type_to_extensions_map_.erase(it++);
and not increment |it| in the next for-loop iteration.

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

Done.

+      }
+    }
+  }
+}
+
+void MDnsAPI::OnMDnsEvent(const std::string& service_type,

[Matt Perry, 2013/08/30 00:43:29]

This is where filtered events would come in really handy. You would just set up
the right filter, then BroadcastEvent and the EventRouter will take care of
sending it to the right extensions.

(And you wouldn't need service_type_to_extensions_map_ anymore, I believe.)

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

Looking into using this. Does seem promising, but I haven't figured out how to
use filters in an .idl file yet. It seems they're only ever using in the
webnavigation API right now.

[Matt Perry, 2013/09/03 22:24:04]

Oh you're right, we don't have support for filters in .idl files yet. Also,
you'll have to add a new filter type (see EventFilteringInfo and related data
structures) for service type.

As for the .idl, you can either use a .json file instead, or add support to the
.idl compiler to handle your new filter type.

+                          const NsdRegistry::NsdServiceList& services) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (services.size() > 0 &&
+      service_type_to_extensions_map_.find(service_type) !=
+      service_type_to_extensions_map_.end()) {
+    const std::set<std::string>& extensions =
+        service_type_to_extensions_map_[service_type];
+    for (std::set<std::string>::iterator it = extensions.begin();
+         it != extensions.end(); ++it) {
+      std::vector<linked_ptr<mdns::MDnsService> > args;
+      for (NsdRegistry::NsdServiceList::const_iterator it = services.begin();
+           it != services.end(); ++it) {
+        linked_ptr<mdns::MDnsService> mdns_service =
+            make_linked_ptr(new mdns::MDnsService);
+        // TODO(justinlin, mfoltz): Correctly fill in service info.

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

The registry should already have correctly filled mdns::MDnsService objects.

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

The TODO is to copy the information from a NsdServiceList::Service object to the
base::Dictionary object.

+        mdns_service->service_name = service_type;
+        args.push_back(mdns_service);
+      }
+      scoped_ptr<base::ListValue> results = mdns::OnServiceList::Create(args);
+      scoped_ptr<Event> event(
+          new Event(mdns::OnServiceList::kEventName, results.Pass()));
+      extensions::ExtensionSystem::Get(profile_)->event_router()->
+          DispatchEventToExtension(*it, event.Pass());
+    }
+  }
+}
+
+}  // namespace extensions