Bug 1351190 - Associate printing actor with SystemGroup r=bevistseng,smaug

MozReview-Commit-ID: VNLEKCFrtX

--HG--
extra : rebase_source : 7b2fdc5bae4fcac61a03c37ec9056f47f6566b57

dom/ipc/ContentChild.cpp

@@ -521,6 +521,14 @@ ContentChild::RecvSetXPCOMProcessAttributes(const XPCOMInitData& aXPCOMInit,
   mLookAndFeelCache = aLookAndFeelIntCache;
   InitXPCOM(aXPCOMInit, aInitialData);
   InitGraphicsDeviceData(aXPCOMInit.contentDeviceData());
+
+#ifdef NS_PRINTING
+  // Force the creation of the nsPrintingProxy so that it's IPC counterpart,
+  // PrintingParent, is always available for printing initiated from the parent.
+  // Create nsPrintingProxy instance later than the SystemGroup initialization.
+  RefPtr<nsPrintingProxy> printingProxy = nsPrintingProxy::GetInstance();
+#endif
+
   return IPC_OK();
 }
 
@@ -602,12 +610,6 @@ ContentChild::Init(MessageLoop* aIOLoop,
   mID = aChildID;
   mIsForBrowser = aIsForBrowser;
 
-#ifdef NS_PRINTING
-  // Force the creation of the nsPrintingProxy so that it's IPC counterpart,
-  // PrintingParent, is always available for printing initiated from the parent.
-  RefPtr<nsPrintingProxy> printingProxy = nsPrintingProxy::GetInstance();
-#endif
-
   SetProcessName(NS_LITERAL_STRING("Web Content"), true);
 
   return true;

toolkit/components/printingui/ipc/nsPrintingProxy.cpp

@@ -63,6 +63,10 @@ nsPrintingProxy::GetInstance()
 nsresult
 nsPrintingProxy::Init()
 {
+  ContentChild::GetSingleton()->SetEventTargetForActor(this,
+    SystemGroup::EventTargetFor(mozilla::TaskCategory::Other));
+  MOZ_ASSERT(this->GetActorEventTarget());
+
   mozilla::Unused << ContentChild::GetSingleton()->SendPPrintingConstructor(this);
   return NS_OK;
 }