Create libsampler as V8 sampler library.

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 6278 matching lines @@
    */
   void VisitHandlesForPartialDependence(PersistentHandleVisitor* visitor);
 
   /**
    * Iterates through all the persistent handles in the current isolate's heap
    * that have class_ids and are weak to be marked as inactive if there is no
    * pending activity for the handle.
    */
   void VisitWeakHandles(PersistentHandleVisitor* visitor);
 
+  /**
+   * Check if this isolate is in use.

[alph, 2016/05/03 18:48:07]

The description doesn't add much information to the function name. Could you
write more detailed info on what 'in use' means.

[lpy, 2016/05/04 00:09:23]

Done.

+   */
+  bool IsInUse();
+
  private:
   template <class K, class V, class Traits>
   friend class PersistentValueMapBase;
 
   Isolate();
   Isolate(const Isolate&);
   ~Isolate();
   Isolate& operator=(const Isolate&);
   void* operator new(size_t size);
   void operator delete(void*, size_t);
@@ skipping 2465 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // INCLUDE_V8_H_