ServiceWorker: Enable UseCounter for ServiceWorkerGlobalScope

content/browser/service_worker/service_worker_version.h

Index: content/browser/service_worker/service_worker_version.h
diff --git a/content/browser/service_worker/service_worker_version.h b/content/browser/service_worker/service_worker_version.h
index f8f95eff88a97be3d681e9a1bebfb4d35c49b5d9..d84370094e864c6f480169fb7a05c2db4fa457fe 100644
--- a/content/browser/service_worker/service_worker_version.h
+++ b/content/browser/service_worker/service_worker_version.h
@@ -466,6 +466,12 @@ class CONTENT_EXPORT ServiceWorkerVersion
   // for both A and B case. So the methods and attributes are available in JS.
   NavigationPreloadSupportStatus GetNavigationPreloadSupportStatus() const;
 
+  void CountFeature(uint32_t feature);
+  void set_used_features(std::set<uint32_t> used_features) {
+    used_features_ = used_features;
+  }
+  std::set<uint32_t> used_features() const { return used_features_; }
+
  private:
   friend class base::RefCounted<ServiceWorkerVersion>;
   friend class ServiceWorkerMetrics;
@@ -844,6 +850,10 @@ class CONTENT_EXPORT ServiceWorkerVersion
   // FinishStartWorker().
   base::Optional<ServiceWorkerMetrics::EventType> start_worker_first_purpose_;
 
+  // This is the set of features that this worker has used. The values must be
+  // from blink::UseCounter::Feature enum.

[falken, 2017/02/08 05:01:53]

Can we mention this is the used features that were (1) used up until
installation of this version completed, or (2) used during the lifetime of
|this|.

If that's correct?

[nhiroki, 2017/02/09 05:11:32]

That's correct. Updated.

+  std::set<uint32_t> used_features_;
+
   base::WeakPtrFactory<ServiceWorkerVersion> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceWorkerVersion);