diff --git a/dom/bindings/Codegen.py b/dom/bindings/Codegen.py
index 53bb341ade73..68de0f2c31d9 100644
--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -1301,6 +1301,17 @@ class CGClassHasInstanceHook(CGAbstractStaticMethod):
 def isChromeOnly(m):
     return m.getExtendedAttribute("ChromeOnly")
 
+def getAvailableInTestFunc(obj):
+    availableIn = obj.getExtendedAttribute("AvailableIn")
+    if availableIn is None:
+        return None
+    assert isinstance(availableIn, list) and len(availableIn) == 1
+    if availableIn[0] == "PrivilegedApps":
+        return "IsInPrivilegedApp"
+    if availableIn[0] == "CertifiedApps":
+        return "IsInCertifiedApp"
+    raise TypeError("Unknown AvailableIn value '%s'" % availableIn[0])
+
 class MemberCondition:
     """
     An object representing the condition for a member to actually be
@@ -2118,6 +2129,9 @@ class CGConstructorEnabled(CGAbstractMethod):
             conditions.append("%s(aCx, aObj)" % func[0])
         if iface.getExtendedAttribute("PrefControlled"):
             conditions.append("%s::PrefEnabled()" % self.descriptor.nativeType)
+        availableIn = getAvailableInTestFunc(iface)
+        if availableIn:
+            conditions.append("%s(aCx, aObj)" % availableIn)
         # We should really have some conditions
         assert len(conditions)
         body = CGWrapper(CGList((CGGeneric(cond) for cond in conditions),
diff --git a/dom/bindings/Configuration.py b/dom/bindings/Configuration.py
index 2926be233e88..1360ac029843 100644
--- a/dom/bindings/Configuration.py
+++ b/dom/bindings/Configuration.py
@@ -492,7 +492,8 @@ class Descriptor(DescriptorProvider):
         return (self.interface.getExtendedAttribute("Pref") or
                 self.interface.getExtendedAttribute("ChromeOnly") or
                 self.interface.getExtendedAttribute("Func") or
-                self.interface.getExtendedAttribute("PrefControlled"))
+                self.interface.getExtendedAttribute("PrefControlled") or
+                self.interface.getExtendedAttribute("AvailableIn"))
 
 # Some utility methods
 def getTypesFromDescriptor(descriptor):
diff --git a/dom/bindings/parser/WebIDL.py b/dom/bindings/parser/WebIDL.py
index f0369d92ac05..90da33ea6445 100644
--- a/dom/bindings/parser/WebIDL.py
+++ b/dom/bindings/parser/WebIDL.py
@@ -977,6 +977,7 @@ class IDLInterface(IDLObjectWithScope):
                   identifier == "JSImplementation" or
                   identifier == "HeaderFile" or
                   identifier == "NavigatorProperty" or
+                  identifier == "AvailableIn" or
                   identifier == "Func"):
                 # Known extended attributes that take a string value
                 if not attr.hasValue():
@@ -2813,6 +2814,7 @@ class IDLAttribute(IDLInterfaceMember):
               identifier == "Constant" or
               identifier == "Func" or
               identifier == "Frozen" or
+              identifier == "AvailableIn" or
               identifier == "NewObject"):
             # Known attributes that we don't need to do anything with here
             pass
@@ -3363,6 +3365,7 @@ class IDLMethod(IDLInterfaceMember, IDLScope):
               identifier == "ChromeOnly" or
               identifier == "Pref" or
               identifier == "Func" or
+              identifier == "AvailableIn" or
               identifier == "Pure" or
               identifier == "CrossOriginCallable" or
               identifier == "WebGLHandlesContextLoss"):
diff --git a/dom/bindings/test/TestCodeGen.webidl b/dom/bindings/test/TestCodeGen.webidl
index cf5ca157672a..1eabe0cc767c 100644
--- a/dom/bindings/test/TestCodeGen.webidl
+++ b/dom/bindings/test/TestCodeGen.webidl
@@ -10,6 +10,7 @@ typedef TestInterface? NullableTestInterface;
 
 interface TestExternalInterface;
 
+[AvailableIn=PrivilegedApps, Pref="xyz"]
 interface TestRenamedInterface {
 };
 
@@ -105,6 +106,7 @@ interface OnlyForUseInConstructor {
  Constructor(long arg1, IndirectlyImplementedInterface iface),
  Constructor(Date arg1),
  // Constructor(long arg1, long arg2, (TestInterface or OnlyForUseInConstructor) arg3),
+ AvailableIn=CertifiedApps,
  NamedConstructor=Test,
  NamedConstructor=Test(DOMString str),
  NamedConstructor=Test2(DictForConstructor dict, any any1, object obj1,