Bug 778044. Add a way to pref off Paris binding constructor objects. r=peterv

dom/base/nsDOMClassInfo.cpp

@@ -4639,7 +4639,8 @@ nsDOMClassInfo::Init()
   mozilla::dom::oldproxybindings::Register(nameSpaceManager);
 
   if (!AzureCanvasEnabled()) {
-    nameSpaceManager->RegisterDefineDOMInterface(NS_LITERAL_STRING("CanvasRenderingContext2D"), NULL);
+    nameSpaceManager->RegisterDefineDOMInterface(NS_LITERAL_STRING("CanvasRenderingContext2D"),
+                                                 nullptr, nullptr);
   }
 
   sIsInitialized = true;
@@ -6790,6 +6791,10 @@ nsWindowSH::GlobalResolve(nsGlobalWindow *aWin, JSContext *cx,
         return NS_OK;
       }
 
+      if (name_struct->mPrefEnabled && !(*name_struct->mPrefEnabled)()) {
+        return NS_OK;
+      }
+
       if (mozilla::dom::DefineConstructor(cx, obj, define, &rv)) {
         *did_resolve = NS_SUCCEEDED(rv);
 

dom/base/nsScriptNameSpaceManager.cpp

@@ -781,7 +781,8 @@ nsScriptNameSpaceManager::Observe(nsISupports* aSubject, const char* aTopic,
 
 void
 nsScriptNameSpaceManager::RegisterDefineDOMInterface(const nsAFlatString& aName,
-    mozilla::dom::DefineInterface aDefineDOMInterface)
+    mozilla::dom::DefineInterface aDefineDOMInterface,
+    mozilla::dom::PrefEnabled aPrefEnabled)
 {
   nsGlobalNameStruct *s = AddToHash(&mGlobalNames, &aName);
   if (s) {
@@ -789,5 +790,6 @@ nsScriptNameSpaceManager::RegisterDefineDOMInterface(const nsAFlatString& aName,
       s->mType = nsGlobalNameStruct::eTypeNewDOMBinding;
     }
     s->mDefineDOMInterface = aDefineDOMInterface;
+    s->mPrefEnabled = aPrefEnabled;
   }
 }

dom/base/nsScriptNameSpaceManager.h

@@ -68,6 +68,7 @@ struct nsGlobalNameStruct
 
   // For new style DOM bindings.
   mozilla::dom::DefineInterface mDefineDOMInterface;
+  mozilla::dom::PrefEnabled mPrefEnabled; // May be null if not pref controlled
 
 private:
 
@@ -139,7 +140,8 @@ public:
   nsGlobalNameStruct* GetConstructorProto(const nsGlobalNameStruct* aStruct);
 
   void RegisterDefineDOMInterface(const nsAFlatString& aName,
-    mozilla::dom::DefineInterface aDefineDOMInterface);
+    mozilla::dom::DefineInterface aDefineDOMInterface,
+    mozilla::dom::PrefEnabled aPrefEnabled);
 
 private:
   // Adds a new entry to the hash and returns the nsGlobalNameStruct

dom/bindings/Codegen.py

@@ -1338,6 +1338,24 @@ class CGDefineDOMInterfaceMethod(CGAbstractMethod):
   *aEnabled = true;
   return !!%s(aCx, global, aReceiver);""" % (getter))
 
+class CGPrefEnabled(CGAbstractMethod):
+    """
+    A method for testing whether the preference controlling this
+    interface is enabled.  When it's not, the interface should not be
+    visible on the global.
+    """
+    def __init__(self, descriptor):
+        CGAbstractMethod.__init__(self, descriptor, 'PrefEnabled', 'bool', [])
+
+    def declare(self):
+        return CGAbstractMethod.declare(self)
+
+    def define(self):
+        return CGAbstractMethod.define(self)
+
+    def definition_body(self):
+        return "  return %s::PrefEnabled();" % self.descriptor.nativeType
+
 class CGIsMethod(CGAbstractMethod):
     def __init__(self, descriptor):
         args = [Argument('JSObject*', 'obj')]
@@ -4999,6 +5017,11 @@ class CGDescriptor(CGThing):
 
         if descriptor.interface.hasInterfaceObject():
             cgThings.append(CGDefineDOMInterfaceMethod(descriptor))
+            if (not descriptor.interface.isExternal() and
+                # Workers stuff is never pref-controlled
+                not descriptor.workers and
+                descriptor.interface.getExtendedAttribute("PrefControlled") is not None):
+                cgThings.append(CGPrefEnabled(descriptor))
 
         if descriptor.interface.hasInterfacePrototypeObject():
             cgThings.append(CGNativePropertyHooks(descriptor))
@@ -5310,12 +5333,16 @@ class CGRegisterProtos(CGAbstractMethod):
 
     def _defineMacro(self):
        return """
-#define REGISTER_PROTO(_dom_class) \\
+#define REGISTER_PROTO(_dom_class, _pref_check) \\
-  aNameSpaceManager->RegisterDefineDOMInterface(NS_LITERAL_STRING(#_dom_class), _dom_class##Binding::DefineDOMInterface);\n\n"""
+  aNameSpaceManager->RegisterDefineDOMInterface(NS_LITERAL_STRING(#_dom_class), _dom_class##Binding::DefineDOMInterface, _pref_check);\n\n"""
     def _undefineMacro(self):
         return "\n#undef REGISTER_PROTO"
     def _registerProtos(self):
-        lines = ["REGISTER_PROTO(%s);" % desc.name
+        def getPrefCheck(desc):
+            if desc.interface.getExtendedAttribute("PrefControlled") is None:
+                return "nullptr"
+            return "%sBinding::PrefEnabled" % desc.name
+        lines = ["REGISTER_PROTO(%s, %s);" % (desc.name, getPrefCheck(desc))
                  for desc in self.config.getDescriptors(hasInterfaceObject=True,
                                                         isExternal=False,
                                                         workers=False,

dom/bindings/parser/WebIDL.py

@@ -738,6 +738,9 @@ class IDLInterface(IDLObjectWithScope):
                 return loopPoint
         return None
 
+    def getExtendedAttribute(self, name):
+        return self._extendedAttrDict.get(name, None)
+
 class IDLDictionary(IDLObjectWithScope):
     def __init__(self, location, parentScope, name, parent, members):
         assert isinstance(parentScope, IDLScope)

js/xpconnect/src/dombindingsgen.py

@@ -736,7 +736,7 @@ def writeStubFile(filename, config, interfaces):
                 "Register(nsScriptNameSpaceManager* aNameSpaceManager)\n"
                 "{\n"
                 "#define REGISTER_PROTO(_dom_class) \\\n"
-                "    aNameSpaceManager->RegisterDefineDOMInterface(NS_LITERAL_STRING(#_dom_class), _dom_class##Wrapper::DefineDOMInterface);\n\n"""
+                "    aNameSpaceManager->RegisterDefineDOMInterface(NS_LITERAL_STRING(#_dom_class), _dom_class##Wrapper::DefineDOMInterface, nullptr);\n\n"""
                 "\n")
         for clazz in config.list_classes.itervalues():
             f.write("    REGISTER_PROTO(%s);\n" % clazz.name)

js/xpconnect/src/xpcpublic.h

@@ -345,6 +345,9 @@ inline bool IsDOMProxy(JSObject *obj)
 typedef bool
 (*DefineInterface)(JSContext *cx, JSObject *global, bool *enabled);
 
+typedef bool
+(*PrefEnabled)();
+
 extern bool
 DefineStaticJSVals(JSContext *cx);
 void