Convert resources to take an instance key instead of an Instance*.

ppapi/cpp/dev/device_ref_dev.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PPAPI_CPP_DEV_DEVICE_REF_DEV_H_
 #define PPAPI_CPP_DEV_DEVICE_REF_DEV_H_
 
 #include "ppapi/c/dev/ppb_device_ref_dev.h"
 #include "ppapi/cpp/resource.h"
 #include "ppapi/cpp/var.h"
 
 namespace pp {
 
 class DeviceRef_Dev : public Resource {
  public:
   DeviceRef_Dev();
 
   explicit DeviceRef_Dev(PP_Resource resource);
 
-  struct PassRef {};
-
   DeviceRef_Dev(PassRef, PP_Resource resource);
 
   DeviceRef_Dev(const DeviceRef_Dev& other);
 
   virtual ~DeviceRef_Dev();
 
   PP_DeviceType_Dev GetType() const;
 
   Var GetName() const;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_DEV_DEVICE_REF_DEV_H_