PPAPI: Make PPB_MessageLoop_Dev::GetForMainThread work

ppapi/shared_impl/resource.cc

Index: ppapi/shared_impl/resource.cc
diff --git a/ppapi/shared_impl/resource.cc b/ppapi/shared_impl/resource.cc
index 6f095f77c0dcc8d471c0328e76e3e816fcee61f9..5c9f738568a6d62e5f74c574167ae7e9be464140 100644
--- a/ppapi/shared_impl/resource.cc
+++ b/ppapi/shared_impl/resource.cc
@@ -12,7 +12,7 @@ namespace ppapi {
 
 Resource::Resource(ResourceObjectType type, PP_Instance instance)
     : host_resource_(HostResource::MakeInstanceOnly(instance)) {
-  // The instance should always be valid (nonzero).
+  // The instance should be valid (nonzero).
   DCHECK(instance);
 
   pp_resource_ = PpapiGlobals::Get()->GetResourceTracker()->AddResource(this);
@@ -40,6 +40,10 @@ Resource::Resource(ResourceObjectType type, const HostResource& host_resource)
   }
 }
 
+Resource::Resource(Untracked) {
+  pp_resource_ = PpapiGlobals::Get()->GetResourceTracker()->AddResource(this);
+}
+
 Resource::~Resource() {
   PpapiGlobals::Get()->GetResourceTracker()->RemoveResource(this);
 }