Bug 1424768 - telemetry accessible tree update times, r=jamie, francois

accessible/base/NotificationController.cpp

@@ -612,6 +612,8 @@ NotificationController::ProcessMutationEvents()
 void
 NotificationController::WillRefresh(mozilla::TimeStamp aTime)
 {
+  Telemetry::AutoTimer<Telemetry::A11Y_TREE_UPDATE_TIMING_MS> timer;
+
   AUTO_PROFILER_LABEL("NotificationController::WillRefresh", OTHER);
 
   // If the document accessible that notification collector was created for is

toolkit/components/telemetry/Histograms.json

@@ -43,6 +43,16 @@
     "bug_numbers": [1423989],
     "alert_emails": ["dbolter@mozilla.com"]
   },
+  "A11Y_TREE_UPDATE_TIMING_MS" : {
+    "record_in_processes": ["main", "content"],
+    "alert_emails": ["asurkov@mozilla.com"],
+    "bug_numbers": [1424768],
+    "expires_in_version": "never",
+    "description": "The amount of time taken to update the accessibility tree (ms)",
+    "kind" : "exponential",
+    "high": 60000,
+    "n_buckets": 50
+  },
   "ADDON_CONTENT_POLICY_SHIM_BLOCKING_LOADING_MS": {
     "record_in_processes": ["main", "content"],
     "expires_in_version": "58",