Bug 1533302 part 3 - Use UniquePtr for CompartmentPrivate's XPCWrappedNativeScope. r=mccr8

`CompartmentPrivate::GetScope()` was added so callers don't have to do `scope.get()`
manually. The `scope` field is now private and was renamed to `mScope`.

Also replaces some `CompartmentPrivate::Get(obj)->scope` instances with
`ObjectScope(obj)`. It's equivalent but shorter.

Differential Revision: https://phabricator.services.mozilla.com/D22664

--HG--
extra : moz-landing-system : lando

js/xpconnect/src/XPCJSRuntime.cpp

@@ -184,12 +184,10 @@ class AsyncFreeSnowWhite : public Runnable {
 
 namespace xpc {
 
-CompartmentPrivate::CompartmentPrivate(JS::Compartment* c,
-                                       XPCWrappedNativeScope* scope,
-                                       mozilla::BasePrincipal* origin,
-                                       const SiteIdentifier& site)
+CompartmentPrivate::CompartmentPrivate(
+    JS::Compartment* c, mozilla::UniquePtr<XPCWrappedNativeScope> scope,
+    mozilla::BasePrincipal* origin, const SiteIdentifier& site)
     : originInfo(origin, site),
-      scope(scope),
       wantXrays(false),
       allowWaivers(true),
       isWebExtensionContentScript(false),
@@ -199,14 +197,14 @@ CompartmentPrivate::CompartmentPrivate(JS::Compartment* c,
       hasExclusiveExpandos(false),
       universalXPConnectEnabled(false),
       wasShutdown(false),
-      mWrappedJSMap(JSObject2WrappedJSMap::newMap(XPC_JS_MAP_LENGTH)) {
+      mWrappedJSMap(JSObject2WrappedJSMap::newMap(XPC_JS_MAP_LENGTH)),
+      mScope(std::move(scope)) {
   MOZ_COUNT_CTOR(xpc::CompartmentPrivate);
 }
 
 CompartmentPrivate::~CompartmentPrivate() {
   MOZ_COUNT_DTOR(xpc::CompartmentPrivate);
   delete mWrappedJSMap;
-  delete scope;
 }
 
 void CompartmentPrivate::SystemIsBeingShutDown() {
@@ -244,9 +242,9 @@ void RealmPrivate::Init(HandleObject aGlobal, const SiteIdentifier& aSite) {
   if (CompartmentPrivate* priv = CompartmentPrivate::Get(c)) {
     MOZ_ASSERT(priv->originInfo.IsSameOrigin(principal));
   } else {
-    auto* scope = new XPCWrappedNativeScope(c, aGlobal);
-    priv =
-        new CompartmentPrivate(c, scope, BasePrincipal::Cast(principal), aSite);
+    auto scope = mozilla::MakeUnique<XPCWrappedNativeScope>(c, aGlobal);
+    priv = new CompartmentPrivate(c, std::move(scope),
+                                  BasePrincipal::Cast(principal), aSite);
     JS_SetCompartmentPrivate(c, priv);
   }
 }
@@ -593,10 +591,8 @@ bool EnableUniversalXPConnect(JSContext* cx) {
   // but we define it when UniversalXPConnect is enabled to support legacy
   // tests.
   Compartment* comp = js::GetContextCompartment(cx);
-  XPCWrappedNativeScope* scope = CompartmentPrivate::Get(comp)->scope;
-  if (!scope) {
-    return true;
-  }
+  XPCWrappedNativeScope* scope = CompartmentPrivate::Get(comp)->GetScope();
+  MOZ_ASSERT(scope);
   scope->ForcePrivilegedComponents();
   return scope->AttachComponentsObject(cx);
 }
@@ -986,7 +982,7 @@ void XPCJSRuntime::WeakPointerCompartmentCallback(JSContext* cx,
 void CompartmentPrivate::UpdateWeakPointersAfterGC() {
   mRemoteProxies.sweep();
   mWrappedJSMap->UpdateWeakPointersAfterGC();
-  scope->UpdateWeakPointersAfterGC();
+  mScope->UpdateWeakPointersAfterGC();
 }
 
 void XPCJSRuntime::CustomOutOfMemoryCallback() {

js/xpconnect/src/XPCMaps.h

@@ -505,8 +505,7 @@ class JSObject2JSObjectMap {
     if (!mTable.add(p, key, value)) {
       return nullptr;
     }
-    MOZ_ASSERT(xpc::CompartmentPrivate::Get(key)->scope->mWaiverWrapperMap ==
-               this);
+    MOZ_ASSERT(xpc::ObjectScope(key)->mWaiverWrapperMap == this);
     return value;
   }
 

js/xpconnect/src/XPCWrappedNative.cpp

@@ -183,7 +183,7 @@ nsresult XPCWrappedNative::WrapNewGlobal(xpcObjectHelper& nativeHelper,
   if (!global) {
     return NS_ERROR_FAILURE;
   }
-  XPCWrappedNativeScope* scope = CompartmentPrivate::Get(global)->scope;
+  XPCWrappedNativeScope* scope = ObjectScope(global);
 
   // Immediately enter the global's realm, so that everything else we
   // create ends up there.

js/xpconnect/src/XPCWrappedNativeScope.cpp

@@ -217,8 +217,7 @@ namespace xpc {
 JSObject* GetXBLScope(JSContext* cx, JSObject* contentScopeArg) {
   JS::RootedObject contentScope(cx, contentScopeArg);
   JSAutoRealm ar(cx, contentScope);
-  XPCWrappedNativeScope* nativeScope =
-      CompartmentPrivate::Get(contentScope)->scope;
+  XPCWrappedNativeScope* nativeScope = ObjectScope(contentScope);
 
   RootedObject scope(cx, nativeScope->EnsureContentXBLScope(cx));
   NS_ENSURE_TRUE(scope, nullptr);  // See bug 858642.
@@ -251,7 +250,7 @@ JSObject* GetUAWidgetScope(JSContext* cx, nsIPrincipal* principal) {
 
 bool AllowContentXBLScope(JS::Realm* realm) {
   JS::Compartment* comp = GetCompartmentForRealm(realm);
-  XPCWrappedNativeScope* scope = CompartmentPrivate::Get(comp)->scope;
+  XPCWrappedNativeScope* scope = CompartmentPrivate::Get(comp)->GetScope();
   MOZ_ASSERT(scope);
   return scope->AllowContentXBLScope(realm);
 }

js/xpconnect/src/nsXPConnect.cpp

@@ -419,8 +419,8 @@ void xpc::TraceXPCGlobal(JSTracer* trc, JSObject* obj) {
   // We might be called from a GC during the creation of a global, before we've
   // been able to set up the compartment private.
   if (xpc::CompartmentPrivate* priv = xpc::CompartmentPrivate::Get(obj)) {
-    MOZ_ASSERT(priv->scope);
-    priv->scope->TraceInside(trc);
+    MOZ_ASSERT(priv->GetScope());
+    priv->GetScope()->TraceInside(trc);
   }
 }
 
@@ -514,8 +514,7 @@ bool InitGlobalObject(JSContext* aJSContext, JS::Handle<JSObject*> aGlobal,
 
   if (!(aFlags & xpc::OMIT_COMPONENTS_OBJECT)) {
     // XPCCallContext gives us an active request needed to save/restore.
-    if (!CompartmentPrivate::Get(aGlobal)->scope->AttachComponentsObject(
-            aJSContext) ||
+    if (!ObjectScope(aGlobal)->AttachComponentsObject(aJSContext) ||
         !XPCNativeWrapper::AttachNewConstructorObject(aJSContext, aGlobal)) {
       return UnexpectedFailure(false);
     }

js/xpconnect/src/xpcprivate.h

@@ -2668,7 +2668,8 @@ class CompartmentPrivate {
   CompartmentPrivate(const CompartmentPrivate&) = delete;
 
  public:
-  CompartmentPrivate(JS::Compartment* c, XPCWrappedNativeScope* scope,
+  CompartmentPrivate(JS::Compartment* c,
+                     mozilla::UniquePtr<XPCWrappedNativeScope> scope,
                      mozilla::BasePrincipal* origin,
                      const mozilla::SiteIdentifier& site);
 
@@ -2700,14 +2701,12 @@ class CompartmentPrivate {
     // Don't share if we have any weird state set.
     return !wantXrays && !isWebExtensionContentScript &&
            !isContentXBLCompartment && !isUAWidgetCompartment &&
-           !universalXPConnectEnabled && scope->XBLScopeStateMatches(principal);
+           !universalXPConnectEnabled &&
+           mScope->XBLScopeStateMatches(principal);
   }
 
   CompartmentOriginInfo originInfo;
 
-  // Our XPCWrappedNativeScope.
-  XPCWrappedNativeScope* scope;
-
   // Controls whether this compartment gets Xrays to same-origin. This behavior
   // is deprecated, but is still the default for sandboxes for compatibity
   // reasons.
@@ -2771,12 +2770,17 @@ class CompartmentPrivate {
       RemoteProxyMap;
   RemoteProxyMap& GetRemoteProxyMap() { return mRemoteProxies; }
 
+  XPCWrappedNativeScope* GetScope() { return mScope.get(); }
+
  private:
   JSObject2WrappedJSMap* mWrappedJSMap;
 
   // Cache holding proxy objects for Window objects (and their Location oject)
   // that are loaded in a different process.
   RemoteProxyMap mRemoteProxies;
+
+  // Our XPCWrappedNativeScope.
+  mozilla::UniquePtr<XPCWrappedNativeScope> mScope;
 };
 
 bool IsUniversalXPConnectEnabled(JS::Compartment* compartment);
@@ -2896,7 +2900,7 @@ class RealmPrivate {
 };
 
 inline XPCWrappedNativeScope* ObjectScope(JSObject* obj) {
-  return CompartmentPrivate::Get(obj)->scope;
+  return CompartmentPrivate::Get(obj)->GetScope();
 }
 
 JSObject* NewOutObject(JSContext* cx);