Bug 1589407 - Part 1: Avoid calling nsPermissionManager::GetAllForPrincipal() if no permissions are available in the current process; r=baku

Differential Revision: https://phabricator.services.mozilla.com/D50710

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

extensions/permissions/nsPermissionManager.h

@@ -284,6 +284,15 @@ class nsPermissionManager final : public nsIPermissionManager,
   // From ContentChild.
   nsresult RemoveAllFromIPC();
 
+  /**
+   * Returns false if this permission manager wouldn't have the permission
+   * requested available.
+   *
+   * If aType is empty, checks that the permission manager would have all
+   * permissions available for the given principal.
+   */
+  bool PermissionAvailable(nsIPrincipal* aPrincipal, const nsACString& aType);
+
  private:
   virtual ~nsPermissionManager();
 
@@ -518,15 +527,6 @@ class nsPermissionManager final : public nsIPermissionManager,
   template <class T>
   nsresult RemovePermissionEntries(T aCondition);
 
-  /**
-   * Returns false if this permission manager wouldn't have the permission
-   * requested available.
-   *
-   * If aType is nullptr, checks that the permission manager would have all
-   * permissions available for the given principal.
-   */
-  bool PermissionAvailable(nsIPrincipal* aPrincipal, const nsACString& aType);
-
   nsRefPtrHashtable<nsCStringHashKey,
                     mozilla::GenericNonExclusivePromise::Private>
       mPermissionKeyPromiseMap;

toolkit/components/antitracking/AntiTrackingCommon.cpp

@@ -793,6 +793,12 @@ bool CheckAntiTrackingPermission(nsIPrincipal* aPrincipal,
               "permission of type %s for %s",
               aType.get(), _spec),
              aPrincipalURI);
+    if (!permManager->PermissionAvailable(aPrincipal, aType)) {
+      LOG(
+          ("Permission isn't available for this principal in the current "
+           "process"));
+      return false;
+    }
     nsCOMPtr<nsISimpleEnumerator> se;
     nsresult rv =
         permManager->GetAllForPrincipal(aPrincipal, getter_AddRefs(se));