Add async tracing to SWVersion::AddRequest.

content/browser/service_worker/service_worker_metrics.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_metrics.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/strings/string_util.h"
 #include "content/common/service_worker/service_worker_types.h"
@@ skipping 26 matching lines @@
   return ServiceWorkerMetrics::Site::OTHER;
 }
 
 enum EventHandledRatioType {
   EVENT_HANDLED_NONE,
   EVENT_HANDLED_SOME,
   EVENT_HANDLED_ALL,
   NUM_EVENT_HANDLED_RATIO_TYPE,
 };
 
+const char* const kEventTypeNames[] = {"Activate",
+                                       "Install",
+                                       "Fetch",
+                                       "Sync",
+                                       "Notification Click",
+                                       "Push",
+                                       "Geofencing",
+                                       "Service Port Connect",
+                                       "Message"};
+
+static_assert(arraysize(kEventTypeNames) ==
+                  static_cast<int>(ServiceWorkerMetrics::EventType::NUM_TYPES),
+              "Names should match event types");
+
 }  // namespace
 
+const char* ServiceWorkerMetrics::EventTypeToString(EventType event_type) {
+  size_t event_type_as_int = static_cast<size_t>(event_type);
+  DCHECK(event_type_as_int < arraysize(kEventTypeNames));
+  return kEventTypeNames[event_type_as_int];

[nhiroki, 2016/01/25 03:50:23]

switch-case could be more self-contained. That can check whether all enum types
are appropriately handled on compile time like static_assert.

switch (event_type) {
  case EventType::ACTIVATE:
    return "Activate";
  case EventType::INSTALL:
    return "Install";
  ...
}
NOTREACHED() << event_type;
return "Unknown";

[Marijn Kruisselbrink, 2016/01/25 19:17:29]

Done

+}
+
 bool ServiceWorkerMetrics::ShouldExcludeSiteFromHistogram(Site site) {
   return site == ServiceWorkerMetrics::Site::NEW_TAB_PAGE;
 }
 
 bool ServiceWorkerMetrics::ShouldExcludeURLFromHistogram(const GURL& url) {
   return ShouldExcludeSiteFromHistogram(SiteFromURL(url));
 }
 
 void ServiceWorkerMetrics::CountInitDiskCacheResult(bool result) {
   UMA_HISTOGRAM_BOOLEAN("ServiceWorker.DiskCache.InitResult", result);
@@ skipping 217 matching lines @@
   UMA_HISTOGRAM_ENUMERATION("ServiceWorker.URLRequestJob.FallbackedRequestMode",
                             mode, FETCH_REQUEST_MODE_LAST + 1);
 }
 
 void ServiceWorkerMetrics::RecordTimeBetweenEvents(
     const base::TimeDelta& time) {
   UMA_HISTOGRAM_MEDIUM_TIMES("ServiceWorker.TimeBetweenEvents", time);
 }
 
 }  // namespace content