Implement the ServiceWorker "activate" event during activation

content/common/service_worker/service_worker_messages.h

Index: content/common/service_worker/service_worker_messages.h
diff --git a/content/common/service_worker/service_worker_messages.h b/content/common/service_worker/service_worker_messages.h
index 1ece59427832c09c1339e3f4828edfba4a838a65..58544e5a4f18929eb112eaa842495c4416fd2f42 100644
--- a/content/common/service_worker/service_worker_messages.h
+++ b/content/common/service_worker/service_worker_messages.h
@@ -83,6 +83,8 @@ IPC_MESSAGE_CONTROL4(ServiceWorkerMsg_ServiceWorkerRegistrationError,
 // Sent via EmbeddedWorker to dispatch install event.
 IPC_MESSAGE_CONTROL1(ServiceWorkerMsg_InstallEvent, int /* active_version_id */)
 
+IPC_MESSAGE_CONTROL0(ServiceWorkerMsg_ActivateEvent)
+
 // Sent via EmbeddedWorker to dispatch fetch event.
 IPC_MESSAGE_CONTROL1(ServiceWorkerMsg_FetchEvent,
                      content::ServiceWorkerFetchRequest)
@@ -117,6 +119,9 @@ IPC_MESSAGE_CONTROL2(ServiceWorkerHostMsg_RemoveScriptClient,
 IPC_MESSAGE_CONTROL1(ServiceWorkerHostMsg_InstallEventFinished,
                      blink::WebServiceWorkerEventResult)
 
+IPC_MESSAGE_CONTROL1(ServiceWorkerHostMsg_ActivateEventFinished,
+                     blink::WebServiceWorkerEventResult);
+
 // Informs the browser that fetch event handling has finished.
 // Sent via EmbeddedWorker.
 IPC_MESSAGE_CONTROL2(ServiceWorkerHostMsg_FetchEventFinished,