Add a use counter API

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 4111 matching lines @@
   /**
    * Types of garbage collections that can be requested via
    * RequestGarbageCollectionForTesting.
    */
   enum GarbageCollectionType {
     kFullGarbageCollection,
     kMinorGarbageCollection
   };
 
   /**
+   * Features reported via the SetUseCounterCallback callback. Do not chang
+   * assigned numbers of existing items; add new features to the end of this
+   * list.
+   */
+  enum UseCounterFeature {
+    kUseAsm = 0
+  };
+
+  typedef void (*UseCounterCallback)(Isolate* isolate,
+                                     UseCounterFeature feature);
+
+
+  /**
    * Creates a new isolate.  Does not change the currently entered
    * isolate.
    *
    * When an isolate is no longer used its resources should be freed
    * by calling Dispose().  Using the delete operator is not allowed.
    */
   static Isolate* New();
 
   /**
    * Returns the entered isolate for the current thread or NULL in
@@ skipping 248 matching lines @@
    * run when the script call depth decrements to zero.
    */
   void SetAutorunMicrotasks(bool autorun);
 
   /**
    * Experimental: Returns whether the Microtask Work Queue is automatically
    * run when the script call depth decrements to zero.
    */
   bool WillAutorunMicrotasks() const;
 
+  /**
+   * Sets a callback for counting the number of times a feature of V8 is used.
+   */
+  void SetUseCounterCallback(UseCounterCallback callback);
+
  private:
   template<class K, class V, class Traits> friend class PersistentValueMap;
 
   Isolate();
   Isolate(const Isolate&);
   ~Isolate();
   Isolate& operator=(const Isolate&);
   void* operator new(size_t size);
   void operator delete(void*, size_t);
 
@@ skipping 2255 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_