Bug 1392500 - Name the users of setTimeout() in Timer.jsm. r=billm,mccr8

1. Make nsINamed queriable on WrappedJSHolder.
2. Identify callers via |Cu.generateXPCWrappedJS(aCallback).QueryInterface(Ci.nsINamed).name|.

--HG--
extra : amend_source : 5d4201059f66e46c869c30a963921b6f7b91c389

js/xpconnect/src/XPCComponents.cpp

@@ -3182,7 +3182,18 @@ class WrappedJSHolder : public nsISupports
 private:
     virtual ~WrappedJSHolder() {}
 };
-NS_IMPL_ISUPPORTS0(WrappedJSHolder);
+
+NS_IMPL_ADDREF(WrappedJSHolder)
+NS_IMPL_RELEASE(WrappedJSHolder)
+
+// nsINamed is always supported by nsXPCWrappedJSClass.
+// We expose this interface only for the identity in telemetry analysis.
+NS_INTERFACE_TABLE_HEAD(WrappedJSHolder)
+  if (aIID.Equals(NS_GET_IID(nsINamed))) {
+    return mWrappedJS->QueryInterface(aIID, aInstancePtr);
+  }
+NS_INTERFACE_TABLE0(WrappedJSHolder)
+NS_INTERFACE_TABLE_TAIL
 
 NS_IMETHODIMP
 nsXPCComponents_Utils::GenerateXPCWrappedJS(HandleValue aObj, HandleValue aScope,

toolkit/modules/Timer.jsm

@@ -45,8 +45,8 @@ function _setTimeoutOrIsInterval(aCallback, aMilliseconds, aIsInterval,
     },
 
     // nsINamed
-    name: aIsInterval ? "setInterval() in Timer.jsm"
-                      : "setTimeout() in Timer.jsm",
+    name: (aIsInterval ? "setInterval() for " : "setTimeout() for ") +
+            Cu.generateXPCWrappedJS(aCallback).QueryInterface(Ci.nsINamed).name,
   };
 
   timer.initWithCallback(callback, aMilliseconds,