Set up the infrastructure for Extension event metrics.

chrome/browser/extensions/api/dial/dial_api.cc

Index: chrome/browser/extensions/api/dial/dial_api.cc
diff --git a/chrome/browser/extensions/api/dial/dial_api.cc b/chrome/browser/extensions/api/dial/dial_api.cc
index 9d7714e8128896eb5d0df8091789c82db254bfb7..3e3dd17aba4300ea49eb3a680068d53759166095 100644
--- a/chrome/browser/extensions/api/dial/dial_api.cc
+++ b/chrome/browser/extensions/api/dial/dial_api.cc
@@ -105,8 +105,8 @@ void DialAPI::SendEventOnUIThread(const DialRegistry::DeviceList& devices) {
     args.push_back(api_device);
   }
   scoped_ptr<base::ListValue> results = api::dial::OnDeviceList::Create(args);
-  scoped_ptr<Event> event(
-      new Event(dial::OnDeviceList::kEventName, results.Pass()));
+  scoped_ptr<Event> event(new Event(
+      events::UNKNOWN, dial::OnDeviceList::kEventName, results.Pass()));
   EventRouter::Get(profile_)->BroadcastEvent(event.Pass());
 }
 
@@ -136,7 +136,8 @@ void DialAPI::SendErrorOnUIThread(const DialRegistry::DialErrorCode code) {
   }
 
   scoped_ptr<base::ListValue> results = api::dial::OnError::Create(dial_error);
-  scoped_ptr<Event> event(new Event(dial::OnError::kEventName, results.Pass()));
+  scoped_ptr<Event> event(
+      new Event(events::UNKNOWN, dial::OnError::kEventName, results.Pass()));
   EventRouter::Get(profile_)->BroadcastEvent(event.Pass());
 }