Bug 1020622 - Trace black windows' (webidl) event listeners, r=mccr8

content/base/src/nsCCUncollectableMarker.cpp

@@ -440,6 +440,11 @@ TraceActiveWindowGlobal(const uint64_t& aId, nsGlobalWindow*& aWindow, void* aCl
   if (aWindow->GetDocShell() && aWindow->IsOuterWindow()) {
     TraceClosure* closure = static_cast<TraceClosure*>(aClosure);
     aWindow->TraceGlobalJSObject(closure->mTrc);
+    EventListenerManager* elm = aWindow->GetExistingListenerManager();
+    if (elm) {
+      elm->TraceListeners(closure->mTrc);
+    }
+
 #ifdef MOZ_XUL
     nsIDocument* doc = aWindow->GetExtantDoc();
     if (doc && doc->IsXUL()) {

dom/events/EventListenerManager.cpp

@@ -7,6 +7,7 @@
 #undef CreateEvent
 
 #include "mozilla/BasicEvents.h"
+#include "mozilla/CycleCollectedJSRuntime.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/EventListenerManager.h"
 #ifdef MOZ_B2G
@@ -1329,6 +1330,27 @@ EventListenerManager::MarkForCC()
   }
 }
 
+void
+EventListenerManager::TraceListeners(JSTracer* aTrc)
+{
+  uint32_t count = mListeners.Length();
+  for (uint32_t i = 0; i < count; ++i) {
+    const Listener& listener = mListeners.ElementAt(i);
+    JSEventHandler* jsEventHandler = listener.GetJSEventHandler();
+    if (jsEventHandler) {
+      const TypedEventHandler& typedHandler =
+        jsEventHandler->GetTypedEventHandler();
+      if (typedHandler.HasEventHandler()) {
+        mozilla::TraceScriptHolder(typedHandler.Ptr(), aTrc);
+      }
+    } else if (listener.mListenerType == Listener::eWebIDLListener) {
+      mozilla::TraceScriptHolder(listener.mListener.GetWebIDLCallback(), aTrc);
+    }
+    // We might have eWrappedJSListener, but that is the legacy type for
+    // JS implemented event listeners, and trickier to handle here.
+  }
+}
+
 already_AddRefed<nsIScriptGlobalObject>
 EventListenerManager::GetScriptGlobalAndDocument(nsIDocument** aDoc)
 {

dom/events/EventListenerManager.h

@@ -20,6 +20,7 @@ class nsIDOMEvent;
 class nsIEventListenerInfo;
 class nsIScriptContext;
 class nsPIDOMWindow;
+class JSTracer;
 
 struct EventTypeData;
 
@@ -404,6 +405,8 @@ public:
 
   void MarkForCC();
 
+  void TraceListeners(JSTracer* aTrc);
+
   dom::EventTarget* GetTarget() { return mTarget; }
 
 protected:

xpcom/base/CycleCollectedJSRuntime.cpp

@@ -831,6 +831,14 @@ TraceJSHolder(void* aHolder, nsScriptObjectTracer*& aTracer, void* aArg)
   return PL_DHASH_NEXT;
 }
 
+void
+mozilla::TraceScriptHolder(nsISupports* aHolder, JSTracer* aTracer)
+{
+  nsXPCOMCycleCollectionParticipant* participant = nullptr;
+  CallQueryInterface(aHolder, &participant);
+  participant->Trace(aHolder, JsGcTracer(), aTracer);
+}
+
 void
 CycleCollectedJSRuntime::TraceNativeGrayRoots(JSTracer* aTracer)
 {

xpcom/base/CycleCollectedJSRuntime.h

@@ -310,6 +310,8 @@ private:
 
 MOZ_FINISH_NESTED_ENUM_CLASS(CycleCollectedJSRuntime::OOMState)
 
+void TraceScriptHolder(nsISupports* aHolder, JSTracer* aTracer);
+
 } // namespace mozilla
 
 #endif // mozilla_CycleCollectedJSRuntime_h__