Add UMA to record the ratio of how many fetch events are not handled

content/browser/service_worker/service_worker_version.cc

 // Copyright 2013 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_version.h"
 
 #include "base/command_line.h"
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
@@ skipping 348 matching lines @@
   }
   NOTREACHED() << "Unexpected status: " << status;
   return false;
 }
 
 }  // namespace
 
 const int ServiceWorkerVersion::kStartWorkerTimeoutMinutes = 5;
 const int ServiceWorkerVersion::kRequestTimeoutMinutes = 5;
 
+class ServiceWorkerVersion::ServiceWorkerEventMetrics {
+ public:
+  ServiceWorkerEventMetrics() {}
+  ~ServiceWorkerEventMetrics() {
+    ServiceWorkerMetrics::RecordEventStatus(fired_events, handled_events);
+  }
+
+  void RecordEventStatus(bool handled) {
+    ++fired_events;
+    if (handled)
+      ++handled_events;
+  }
+
+ private:
+  size_t fired_events = 0;
+  size_t handled_events = 0;
+  DISALLOW_COPY_AND_ASSIGN(ServiceWorkerEventMetrics);
+};
+
 ServiceWorkerVersion::ServiceWorkerVersion(
     ServiceWorkerRegistration* registration,
     const GURL& script_url,
     int64 version_id,
     base::WeakPtr<ServiceWorkerContextCore> context)
     : version_id_(version_id),
       registration_id_(registration->id()),
       script_url_(script_url),
       scope_(registration->pattern()),
       status_(NEW),
       context_(context),
       script_cache_map_(this, context),
       ping_state_(NOT_PINGING),
+      metrics_(new ServiceWorkerEventMetrics),
       weak_factory_(this) {
   DCHECK(context_);
   DCHECK(registration);
   context_->AddLiveVersion(this);
   embedded_worker_ = context_->embedded_worker_registry()->CreateWorker();
   embedded_worker_->AddListener(this);
 }
 
 ServiceWorkerVersion::~ServiceWorkerVersion() {
   // The user may have closed the tab waiting for SW to start up.
@@ skipping 786 matching lines @@
     const ServiceWorkerResponse& response) {
   TRACE_EVENT1("ServiceWorker",
                "ServiceWorkerVersion::OnFetchEventFinished",
                "Request id", request_id);
   FetchCallback* callback = fetch_callbacks_.Lookup(request_id);
   if (!callback) {
     NOTREACHED() << "Got unexpected message: " << request_id;
     return;
   }
 
+  // TODO(kinuko): Record other event statuses too.
+  const bool handled = (result == SERVICE_WORKER_FETCH_EVENT_RESULT_RESPONSE);
+  metrics_->RecordEventStatus(handled);
+
   scoped_refptr<ServiceWorkerVersion> protect(this);
   callback->Run(SERVICE_WORKER_OK, result, response);
   RemoveCallbackAndStopIfRedundant(&fetch_callbacks_, request_id);
 }
 
 void ServiceWorkerVersion::OnSyncEventFinished(
     int request_id) {
   TRACE_EVENT1("ServiceWorker",
                "ServiceWorkerVersion::OnSyncEventFinished",
                "Request id", request_id);
@@ skipping 680 matching lines @@
         return SERVICE_WORKER_ERROR_ABORT;
       default:
         return SERVICE_WORKER_ERROR_NETWORK;
     }
   }
 
   return default_code;
 }
 
 }  // namespace content