Bug 11833193 add telemetry probe in about:logins for load time of getAllLogins() in the wild.r=mfinkle, p=vladan

mobile/android/chrome/content/aboutLogins.js

@@ -7,6 +7,7 @@ let Ci = Components.interfaces, Cc = Components.classes, Cu = Components.utils;
 Cu.import("resource://gre/modules/Messaging.jsm");
 Cu.import("resource://gre/modules/Services.jsm")
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/TelemetryStopwatch.jsm");
 
 XPCOMUtils.defineLazyGetter(window, "gChromeWin", function()
   window.QueryInterface(Ci.nsIInterfaceRequestor)
@@ -53,7 +54,9 @@ let Logins = {
     emptyBody.classList.add("hidden");
 
     try {
+      TelemetryStopwatch.start("PWMGR_ABOUT_LOGINS_GET_ALL_LOGINS_MS");
       logins = Services.logins.getAllLogins();
+      TelemetryStopwatch.finish("PWMGR_ABOUT_LOGINS_GET_ALL_LOGINS_MS");
     } catch(e) {
       // Master password was not entered
       debug("Master password permissions error: " + e);

toolkit/components/telemetry/Histograms.json

@@ -8223,6 +8223,14 @@
     "extended_statistics_ok": true,
     "description": "Sanitize: Time it takes to sanitize the open windows list (ms)"
   },
+  "PWMGR_ABOUT_LOGINS_GET_ALL_LOGINS_MS": {
+    "expires_in_version": "55",
+    "kind": "exponential",
+    "high": 60000,
+    "n_buckets": 30,
+    "extended_statistics_ok": true,
+    "description": "How long getAllLogins() on about:logins takes for mobile users"
+  },
   "PWMGR_BLOCKLIST_NUM_SITES": {
     "expires_in_version": "never",
     "kind": "exponential",