ServiceWorker: Insert TRACE_EVENT to watch a breakdown of the ServiceWorker's performance on chome:…

content/browser/service_worker/service_worker_fetch_dispatcher.cc

 // 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.
 
 #include "content/browser/service_worker/service_worker_fetch_dispatcher.h"
 
 #include "base/bind.h"
+#include "base/debug/trace_event.h"
 #include "content/browser/service_worker/service_worker_version.h"
 
 namespace content {
 
 ServiceWorkerFetchDispatcher::ServiceWorkerFetchDispatcher(
     scoped_ptr<ServiceWorkerFetchRequest> request,
     ServiceWorkerVersion* version,
     const base::Closure& prepare_callback,
     const FetchCallback& fetch_callback)
     : version_(version),
@@ skipping 32 matching lines @@
   // The previous activation seems to have failed, abort the step
   // with activate error. (The error should be separately reported
   // to the associated documents and association must be dropped
   // at this point)
   DidFinish(SERVICE_WORKER_ERROR_ACTIVATE_WORKER_FAILED,
             SERVICE_WORKER_FETCH_EVENT_RESULT_FALLBACK,
             ServiceWorkerResponse());
 }
 
 void ServiceWorkerFetchDispatcher::DispatchFetchEvent() {
+  TRACE_EVENT_ASYNC_BEGIN0(
+      "ServiceWorker",
+      "ServiceWorkerFetchDispatcher::DispatchFetchEvent",
+      request_.get());
   version_->DispatchFetchEvent(
       *request_.get(),
       base::Bind(&ServiceWorkerFetchDispatcher::DidPrepare,
                  weak_factory_.GetWeakPtr()),
       base::Bind(&ServiceWorkerFetchDispatcher::DidFinish,
                  weak_factory_.GetWeakPtr()));
 }
 
 void ServiceWorkerFetchDispatcher::DidPrepare() {
   DCHECK(!prepare_callback_.is_null());
   base::Closure prepare_callback = prepare_callback_;
   prepare_callback.Run();
 }
 
 void ServiceWorkerFetchDispatcher::DidFinish(
     ServiceWorkerStatusCode status,
     ServiceWorkerFetchEventResult fetch_result,
     const ServiceWorkerResponse& response) {
+  TRACE_EVENT_ASYNC_END0(
+      "ServiceWorker",
+      "ServiceWorkerFetchDispatcher::DispatchFetchEvent",
+      request_.get());
   DCHECK(!fetch_callback_.is_null());
   FetchCallback fetch_callback = fetch_callback_;
   fetch_callback.Run(status, fetch_result, response);
 }
 
 }  // namespace content