Bug 1295980 - Telemetry about the use of SharedWorkers, r=smaug

dom/workers/SharedWorker.cpp

@@ -12,6 +12,7 @@
 #include "mozilla/Preferences.h"
 #include "mozilla/dom/MessagePort.h"
 #include "mozilla/dom/SharedWorkerBinding.h"
+#include "mozilla/Telemetry.h"
 #include "nsContentUtils.h"
 #include "nsIClassInfoImpl.h"
 #include "nsIDOMEvent.h"
@@ -72,6 +73,8 @@ SharedWorker::Constructor(const GlobalObject& aGlobal, JSContext* aCx,
     return nullptr;
   }
 
+  Telemetry::Accumulate(Telemetry::SHARED_WORKER_COUNT, 1);
+
   return sharedWorker.forget();
 }
 

toolkit/components/telemetry/Histograms.json

@@ -9862,6 +9862,13 @@
     "description": "When restoring tabs on startup, reading from sessionstore.js failed, even though the file exists and is not containing an explicitly empty window.",
     "cpp_guard": "ANDROID"
   },
+  "SHARED_WORKER_COUNT": {
+    "alert_emails": ["amarchesini@mozilla.com"],
+    "expires_in_version": "58",
+    "kind": "count",
+    "bug_numbers": [1295980],
+    "description": "Number of the use of SharedWorkers."
+  },
   "FENNEC_SESSIONSTORE_RESTORING_FROM_BACKUP": {
     "alert_emails": ["jh+bugzilla@buttercookie.de"],
     "expires_in_version": "56",