[Not for review] Add traces for crbug.com/726626

content/renderer/service_worker/service_worker_context_client.cc

Index: content/renderer/service_worker/service_worker_context_client.cc
diff --git a/content/renderer/service_worker/service_worker_context_client.cc b/content/renderer/service_worker/service_worker_context_client.cc
index 3db1cf81460c105aa474848fddf55db0b01a57ca..da4e1baa0dbb6adb4dbfcbcda9aecd4c6c6e7a74 100644
--- a/content/renderer/service_worker/service_worker_context_client.cc
+++ b/content/renderer/service_worker/service_worker_context_client.cc
@@ -400,7 +400,10 @@ class ServiceWorkerContextClient::NavigationPreloadRequest final
       : fetch_event_id_(fetch_event_id),
         url_(url),
         url_loader_(std::move(preload_handle->url_loader)),
-        binding_(this, std::move(preload_handle->url_loader_client_request)) {}
+        binding_(this, std::move(preload_handle->url_loader_client_request)) {
+    TRACE_EVENT0("ServiceWorker",
+                 "NavigationPreloadRequest::NavigationPreloadRequest");
+  }
 
   ~NavigationPreloadRequest() override {}
 
@@ -408,6 +411,8 @@ class ServiceWorkerContextClient::NavigationPreloadRequest final
       const ResourceResponseHead& response_head,
       const base::Optional<net::SSLInfo>& ssl_info,
       mojom::DownloadedTempFilePtr downloaded_file) override {
+    TRACE_EVENT0("ServiceWorker",
+                 "NavigationPreloadRequest::OnReceiveResponse");
     DCHECK(!response_);
     DCHECK(!downloaded_file);
     response_ = base::MakeUnique<blink::WebURLResponse>();
@@ -458,12 +463,15 @@ class ServiceWorkerContextClient::NavigationPreloadRequest final
 
   void OnStartLoadingResponseBody(
       mojo::ScopedDataPipeConsumerHandle body) override {
+    TRACE_EVENT0("ServiceWorker",
+                 "NavigationPreloadRequest::OnStartLoadingResponseBody");
     DCHECK(!body_.is_valid());
     body_ = std::move(body);
     MaybeReportResponseToClient();
   }
 
   void OnComplete(const ResourceRequestCompletionStatus& status) override {
+    TRACE_EVENT0("ServiceWorker", "NavigationPreloadRequest::OnComplete");
     if (status.error_code != net::OK) {
       std::string message;
       std::string unsanitized_message;