typesafe call-on-main-thread interface. no cast to/from void* required.

src/trusted/weak_ref/weak_ref.h

 /*
  * Copyright (c) 2011 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // A form of weak reference for use by CallOnMainThread (COMT).  This
 // class is essentially a thread-safe refcounted class that is used to
 // hold pointers to resources that may "go away" due to the plugin
 // instance being destroyed.  Generally resource cleanup should be
@@ skipping 10 matching lines @@
 // destroys all resources associated with the queued callbacks.  The
 // WeakRef resource pointer is released, triggering the dtor for the
 // resource, and the WeakRef reference is also decremented, so that
 // when the COMT callback is invoked, it can discover that the
 // associated callback data is gone, and will just abort by
 // decrementing the last reference to the WeakRef object.
 //
 // In the normal execution, the callback data is present, and
 // ownership is released to the callback function.
 
+#ifndef NATIVE_CLIENT_SRC_TRUSTED_WEAK_REF_WEAK_REF_H_
+#define NATIVE_CLIENT_SRC_TRUSTED_WEAK_REF_WEAK_REF_H_
+
 #include <set>
 
 #include "native_client/src/include/portability.h"
 #include "native_client/src/include/nacl_scoped_ptr.h"
 #include "native_client/src/shared/platform/refcount_base.h"
 #include "native_client/src/shared/platform/nacl_check.h"
 #include "native_client/src/shared/platform/nacl_log.h"
 #include "native_client/src/shared/platform/nacl_sync.h"
 #include "native_client/src/shared/platform/nacl_sync_checked.h"
 
@@ skipping 158 matching lines @@
   WeakRef(WeakRefAnchor* anchor, R* resource)
       : AnchoredResource(anchor),
         resource_(resource) {
     CHECK(resource != NULL);
   }
 
   scoped_ptr<R> resource_;  // NULL when anchor object is destroyed.
 };
 
 }  // namespace nacl
+
+#endif