Set up the infrastructure for Extension event metrics.

chrome/browser/ui/ash/ash_keyboard_controller_proxy.cc

Index: chrome/browser/ui/ash/ash_keyboard_controller_proxy.cc
diff --git a/chrome/browser/ui/ash/ash_keyboard_controller_proxy.cc b/chrome/browser/ui/ash/ash_keyboard_controller_proxy.cc
index e0c9c5cf16c1e136aa93dc847da3e3369d46be77..eae1b08eb69dd9185e792eaa79fada25a4f46299 100644
--- a/chrome/browser/ui/ash/ash_keyboard_controller_proxy.cc
+++ b/chrome/browser/ui/ash/ash_keyboard_controller_proxy.cc
@@ -94,6 +94,7 @@ class AshKeyboardControllerObserver
     event_args->Append(new_bounds.release());
 
     scoped_ptr<extensions::Event> event(new extensions::Event(
+        extensions::events::UNKNOWN,
         virtual_keyboard_private::OnBoundsChanged::kEventName,
         event_args.Pass()));
     event->restrict_to_browser_context = context_;
@@ -201,6 +202,7 @@ void AshKeyboardControllerProxy::SetUpdateInputType(ui::TextInputType type) {
   event_args->Append(input_context.release());
 
   scoped_ptr<extensions::Event> event(new extensions::Event(
+      extensions::events::UNKNOWN,
       virtual_keyboard_private::OnTextInputBoxFocused::kEventName,
       event_args.Pass()));
   event->restrict_to_browser_context = browser_context();