Set up the infrastructure for Extension event metrics.

chrome/browser/extensions/api/experience_sampling_private/experience_sampling.cc

 // Copyright 2014 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/experience_sampling_private/experience_sampling.h"
 
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
@@ skipping 66 matching lines @@
   api::experience_sampling_private::UserDecision decision;
   decision.name = decision_name;
   decision.learn_more = has_viewed_learn_more();
   decision.details = has_viewed_details();
   decision.time = base::Time::Now().ToJsTime();
 
   scoped_ptr<base::ListValue> args(new base::ListValue());
   args->Append(ui_element_.ToValue().release());
   args->Append(decision.ToValue().release());
   scoped_ptr<Event> event(new Event(
-      api::experience_sampling_private::OnDecision::kEventName, args.Pass()));
+      events::UNKNOWN, api::experience_sampling_private::OnDecision::kEventName,
+      args.Pass()));
   EventRouter* router = EventRouter::Get(browser_context_);
   if (router)
     router->BroadcastEvent(event.Pass());
 }
 
 void ExperienceSamplingEvent::CreateOnDisplayedEvent() {
   // Check if this is from an incognito context. If it is, don't create and send
   // any events.
   if (browser_context_ && browser_context_->IsOffTheRecord())
     return;
   scoped_ptr<base::ListValue> args(new base::ListValue());
   args->Append(ui_element_.ToValue().release());
   scoped_ptr<Event> event(new Event(
+      events::UNKNOWN,
       api::experience_sampling_private::OnDisplayed::kEventName, args.Pass()));
   EventRouter* router = EventRouter::Get(browser_context_);
   if (router)
     router->BroadcastEvent(event.Pass());
 }
 
 }  // namespace extensions