Implement the ServiceWorker "activate" event during activation

content/common/service_worker/service_worker_messages.h

 // 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.
 
 // Message definition file, included multiple times, hence no include guard.
 
 #include "base/strings/string16.h"
 #include "content/common/service_worker/service_worker_status_code.h"
 #include "content/common/service_worker/service_worker_types.h"
 #include "ipc/ipc_message_macros.h"
@@ skipping 72 matching lines @@
 // Informs the browser that the scriptable API client is unregistered.
 IPC_MESSAGE_CONTROL2(ServiceWorkerHostMsg_RemoveScriptClient,
                      int /* thread_id */,
                      int /* provider_id */)
 
 // Informs the browser that install event handling has finished.
 // Sent via EmbeddedWorker.
 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,
                      content::ServiceWorkerFetchEventResult,
                      content::ServiceWorkerResponse)
 
 // Messages sent from the browser to the child process.
 
 // Response to ServiceWorkerMsg_RegisterServiceWorker
 IPC_MESSAGE_CONTROL3(ServiceWorkerMsg_ServiceWorkerRegistered,
@@ skipping 10 matching lines @@
 // RegisterServiceWorker / UnregisterServiceWorker handler above.
 IPC_MESSAGE_CONTROL4(ServiceWorkerMsg_ServiceWorkerRegistrationError,
                      int32 /* thread_id */,
                      int32 /* request_id */,
                      blink::WebServiceWorkerError::ErrorType /* code */,
                      base::string16 /* message */)
 
 // 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)
 
 // Sends a 'message' event to a service worker (browser->EmbeddedWorker).
 IPC_MESSAGE_CONTROL3(ServiceWorkerMsg_Message,
                      base::string16 /* message */,
                      std::vector<int> /* sent_message_port_ids */,
                      std::vector<int> /* new_routing_ids */)