Bug 1255709. Simplify the JSContext/GlobalObject handling in ServiceWorkerRegistrationMainThread::GetPushManager a bit. r=bkelly

dom/base/nsGlobalWindow.cpp

@@ -13776,8 +13776,7 @@ nsGlobalWindow::GetExternal(ErrorResult& aRv)
   if (!mExternal) {
     AutoJSContext cx;
     JS::Rooted<JSObject*> jsImplObj(cx);
-    ConstructJSImplementation(cx, "@mozilla.org/sidebar;1",
-                              this, &jsImplObj, aRv);
+    ConstructJSImplementation("@mozilla.org/sidebar;1", this, &jsImplObj, aRv);
     if (aRv.Failed()) {
       return nullptr;
     }

dom/bindings/BindingUtils.cpp

@@ -2259,7 +2259,7 @@ GetContentGlobalForJSImplementedObject(JSContext* cx, JS::Handle<JSObject*> obj,
 }
 
 already_AddRefed<nsIGlobalObject>
-ConstructJSImplementation(JSContext* aCx, const char* aContractId,
+ConstructJSImplementation(const char* aContractId,
                           const GlobalObject& aGlobal,
                           JS::MutableHandle<JSObject*> aObject,
                           ErrorResult& aRv)
@@ -2271,7 +2271,7 @@ ConstructJSImplementation(JSContext* aCx, const char* aContractId,
     return nullptr;
   }
 
-  ConstructJSImplementation(aCx, aContractId, global, aObject, aRv);
+  ConstructJSImplementation(aContractId, global, aObject, aRv);
 
   if (aRv.Failed()) {
     return nullptr;
@@ -2280,11 +2280,13 @@ ConstructJSImplementation(JSContext* aCx, const char* aContractId,
 }
 
 void
-ConstructJSImplementation(JSContext* aCx, const char* aContractId,
+ConstructJSImplementation(const char* aContractId,
                           nsIGlobalObject* aGlobal,
                           JS::MutableHandle<JSObject*> aObject,
                           ErrorResult& aRv)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+
   // Make sure to divorce ourselves from the calling JS while creating and
   // initializing the object, so exceptions from that will get reported
   // properly, since those are never exceptions that a spec wants to be thrown.
@@ -2307,7 +2309,7 @@ ConstructJSImplementation(JSContext* aCx, const char* aContractId,
       do_QueryInterface(implISupports);
     nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal);
     if (gpi) {
-      JS::Rooted<JS::Value> initReturn(aCx);
+      JS::Rooted<JS::Value> initReturn(nsContentUtils::RootingCxForThread());
       rv = gpi->Init(window, &initReturn);
       if (NS_FAILED(rv)) {
         aRv.Throw(rv);

dom/bindings/BindingUtils.h

@@ -2655,13 +2655,13 @@ GetContentGlobalForJSImplementedObject(JSContext* cx, JS::Handle<JSObject*> obj,
                                        nsIGlobalObject** global);
 
 void
-ConstructJSImplementation(JSContext* aCx, const char* aContractId,
+ConstructJSImplementation(const char* aContractId,
                           nsIGlobalObject* aGlobal,
                           JS::MutableHandle<JSObject*> aObject,
                           ErrorResult& aRv);
 
 already_AddRefed<nsIGlobalObject>
-ConstructJSImplementation(JSContext* aCx, const char* aContractId,
+ConstructJSImplementation(const char* aContractId,
                           const GlobalObject& aGlobal,
                           JS::MutableHandle<JSObject*> aObject,
                           ErrorResult& aRv);

dom/bindings/Codegen.py

@@ -14371,7 +14371,7 @@ def genConstructorBody(descriptor, initCall=""):
         """
         JS::Rooted<JSObject*> jsImplObj(cx);
         nsCOMPtr<nsIGlobalObject> globalHolder =
-          ConstructJSImplementation(cx, "${contractId}", global, &jsImplObj, aRv);
+          ConstructJSImplementation("${contractId}", global, &jsImplObj, aRv);
         if (aRv.Failed()) {
           return nullptr;
         }

dom/workers/ServiceWorkerRegistration.cpp

@@ -22,6 +22,7 @@
 #include "nsIServiceWorkerManager.h"
 #include "nsISupportsPrimitives.h"
 #include "nsPIDOMWindow.h"
+#include "nsContentUtils.h"
 
 #include "WorkerPrivate.h"
 #include "Workers.h"
@@ -767,21 +768,10 @@ ServiceWorkerRegistrationMainThread::GetPushManager(ErrorResult& aRv)
       return nullptr;
     }
 
-    AutoJSAPI jsapi;
-    if (NS_WARN_IF(!jsapi.Init(globalObject))) {
-      aRv.Throw(NS_ERROR_FAILURE);
-      return nullptr;
-    }
-
-    JSContext* cx = jsapi.cx();
-
-    JS::RootedObject globalJs(cx, globalObject->GetGlobalJSObject());
-    GlobalObject global(cx, globalJs);
-
     // TODO: bug 1148117.  This will fail when swr is exposed on workers
-    JS::Rooted<JSObject*> jsImplObj(cx);
-    nsCOMPtr<nsIGlobalObject> unused = ConstructJSImplementation(cx, "@mozilla.org/push/PushManager;1",
-                              global, &jsImplObj, aRv);
+    JS::Rooted<JSObject*> jsImplObj(nsContentUtils::RootingCxForThread());
+    ConstructJSImplementation("@mozilla.org/push/PushManager;1",
+                              globalObject, &jsImplObj, aRv);
     if (aRv.Failed()) {
       return nullptr;
     }