extensions: Register 'app' and 'webstore' bindings only if they are available.

extensions/renderer/dispatcher.cc

Index: extensions/renderer/dispatcher.cc
diff --git a/extensions/renderer/dispatcher.cc b/extensions/renderer/dispatcher.cc
index f27eba89d7aa253ff021d15e56cd78abeec0cd75..0c63f63f486ef532d21304c0f8b80eb9a4cc761b 100644
--- a/extensions/renderer/dispatcher.cc
+++ b/extensions/renderer/dispatcher.cc
@@ -1003,8 +1003,11 @@ void Dispatcher::UpdateBindingsForContext(ScriptContext* context) {
     case Feature::BLESSED_WEB_PAGE_CONTEXT: {
       // Web page context; it's too expensive to run the full bindings code.
       // Hard-code that the app and webstore APIs are available...
-      RegisterBinding("app", context);
-      RegisterBinding("webstore", context);
+      if (context->GetAvailability("app").is_available())
+        RegisterBinding("app", context);
+
+      if (context->GetAvailability("webstore").is_available())
+        RegisterBinding("webstore", context);
 
       // ... and that the runtime API might be available if any extension can
       // connect to it.