Set up the infrastructure for Extension event metrics.

extensions/browser/api/bluetooth/bluetooth_private_apitest.cc

Index: extensions/browser/api/bluetooth/bluetooth_private_apitest.cc
diff --git a/extensions/browser/api/bluetooth/bluetooth_private_apitest.cc b/extensions/browser/api/bluetooth/bluetooth_private_apitest.cc
index 85d88be842d24ac0b1e975ad1cd4c76fbf138617..bc080a1ece9d9bc07d83c6eeb75640859ccfc8f0 100644
--- a/extensions/browser/api/bluetooth/bluetooth_private_apitest.cc
+++ b/extensions/browser/api/bluetooth/bluetooth_private_apitest.cc
@@ -101,8 +101,8 @@ class BluetoothPrivateApiTest : public ExtensionApiTest {
 
     scoped_ptr<base::ListValue> args =
         bt_private::OnPairing::Create(pairing_event);
-    scoped_ptr<Event> event(
-        new Event(bt_private::OnPairing::kEventName, args.Pass()));
+    scoped_ptr<Event> event(new Event(
+        events::UNKNOWN, bt_private::OnPairing::kEventName, args.Pass()));
     EventRouter::Get(browser()->profile())->DispatchEventToExtension(
         kTestExtensionId, event.Pass());
   }