Bug 717069 - correct sessionstore-windows-restored usage in TelemetryPing; r=taras

toolkit/components/telemetry/TelemetryPing.js

@@ -634,7 +634,11 @@ TelemetryPing.prototype = {
    */
   uninstall: function uninstall() {
     this.detachObservers()
-    Services.obs.removeObserver(this, "sessionstore-windows-restored");
+    try {
+      Services.obs.removeObserver(this, "sessionstore-windows-restored");
+    } catch (e) {
+      // Already observed this event.
+    }
     Services.obs.removeObserver(this, "profile-before-change");
     Services.obs.removeObserver(this, "private-browsing");
     Services.obs.removeObserver(this, "quit-application-granted");
@@ -674,6 +678,9 @@ TelemetryPing.prototype = {
       }
       break;
     case "sessionstore-windows-restored":
+      Services.obs.removeObserver(this, "sessionstore-windows-restored");
+      // fall through
+    case "test-gather-startup":
       this.gatherStartupInformation();
       break;
     case "idle-daily":

toolkit/components/telemetry/tests/unit/test_TelemetryPing.js

@@ -29,7 +29,7 @@ var gFinished = false;
 
 function telemetry_ping () {
   const TelemetryPing = Cc["@mozilla.org/base/telemetry-ping;1"].getService(Ci.nsIObserver);
-  TelemetryPing.observe(null, "sessionstore-windows-restored", null);
+  TelemetryPing.observe(null, "test-gather-startup", null);
   TelemetryPing.observe(null, "test-ping", SERVER);
 }