Bug 1315140 - Add telemetry for the Safe Browsing shutdown code. r=francois

MozReview-Commit-ID: F9Hv37Mn73P

--HG--
extra : rebase_source : cf65e215a466352c36dfd02fd796f699b825b77d

toolkit/components/telemetry/Histograms.json

@@ -3772,6 +3772,15 @@
     "n_buckets": 10,
     "description": "Time spent per dbservice lookup (ms)"
   },
+  "URLCLASSIFIER_SHUTDOWN_TIME": {
+    "alert_emails": ["safebrowsing-telemetry@mozilla.org"],
+    "expires_in_version": "58",
+    "kind": "exponential",
+    "high": 60000,
+    "n_buckets": 50,
+    "bug_numbers": [1315140],
+    "description": "Time spent per dbservice shutdown (ms)"
+  },
   "URLCLASSIFIER_CL_CHECK_TIME": {
     "alert_emails": ["safebrowsing-telemetry@mozilla.org"],
     "expires_in_version": "never",

toolkit/components/url-classifier/nsUrlClassifierDBService.cpp

@@ -1737,6 +1737,8 @@ nsUrlClassifierDBService::Shutdown()
   if (!gDbBackgroundThread)
     return NS_OK;
 
+  Telemetry::AutoTimer<Telemetry::URLCLASSIFIER_SHUTDOWN_TIME> timer;
+
   mCompleters.Clear();
 
   nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);