Set up the infrastructure for Extension event metrics.

extensions/browser/api/audio/audio_api.cc

Index: extensions/browser/api/audio/audio_api.cc
diff --git a/extensions/browser/api/audio/audio_api.cc b/extensions/browser/api/audio/audio_api.cc
index 6e0da5ae7158d47f103194bb90e9d7830798a62d..d63aaac4fb6a5e9d0d2d77411d7846f6a1f86382 100644
--- a/extensions/browser/api/audio/audio_api.cc
+++ b/extensions/browser/api/audio/audio_api.cc
@@ -38,9 +38,9 @@ AudioService* AudioAPI::GetService() const {
 
 void AudioAPI::OnDeviceChanged() {
   if (EventRouter::Get(browser_context_)) {
-    scoped_ptr<Event> event(new Event(
-        audio::OnDeviceChanged::kEventName,
-        scoped_ptr<base::ListValue>(new base::ListValue())));
+    scoped_ptr<Event> event(
+        new Event(events::UNKNOWN, audio::OnDeviceChanged::kEventName,
+                  scoped_ptr<base::ListValue>(new base::ListValue())));
     EventRouter::Get(browser_context_)->BroadcastEvent(event.Pass());
   }
 }
@@ -48,8 +48,8 @@ void AudioAPI::OnDeviceChanged() {
 void AudioAPI::OnLevelChanged(const std::string& id, int level) {
   if (EventRouter::Get(browser_context_)) {
     scoped_ptr<base::ListValue> args = audio::OnLevelChanged::Create(id, level);
-    scoped_ptr<Event> event(
-        new Event(audio::OnLevelChanged::kEventName, args.Pass()));
+    scoped_ptr<Event> event(new Event(
+        events::UNKNOWN, audio::OnLevelChanged::kEventName, args.Pass()));
     EventRouter::Get(browser_context_)->BroadcastEvent(event.Pass());
   }
 }
@@ -58,8 +58,8 @@ void AudioAPI::OnMuteChanged(bool is_input, bool is_muted) {
   if (EventRouter::Get(browser_context_)) {
     scoped_ptr<base::ListValue> args =
         audio::OnMuteChanged::Create(is_input, is_muted);
-    scoped_ptr<Event> event(
-        new Event(audio::OnMuteChanged::kEventName, args.Pass()));
+    scoped_ptr<Event> event(new Event(
+        events::UNKNOWN, audio::OnMuteChanged::kEventName, args.Pass()));
     EventRouter::Get(browser_context_)->BroadcastEvent(event.Pass());
   }
 }
@@ -67,8 +67,8 @@ void AudioAPI::OnMuteChanged(bool is_input, bool is_muted) {
 void AudioAPI::OnDevicesChanged(const DeviceInfoList& devices) {
   if (EventRouter::Get(browser_context_)) {
     scoped_ptr<base::ListValue> args = audio::OnDevicesChanged::Create(devices);
-    scoped_ptr<Event> event(
-        new Event(audio::OnDevicesChanged::kEventName, args.Pass()));
+    scoped_ptr<Event> event(new Event(
+        events::UNKNOWN, audio::OnDevicesChanged::kEventName, args.Pass()));
     EventRouter::Get(browser_context_)->BroadcastEvent(event.Pass());
   }
 }