Add a use counter API

src/isolate.cc

 // 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.
 
 #include <stdlib.h>
 
 #include "src/v8.h"
 
 #include "src/ast.h"
 #include "src/bootstrapper.h"
@@ skipping 2325 matching lines @@
         v8::MicrotaskCallback callback =
             v8::ToCData<v8::MicrotaskCallback>(callback_info->callback());
         void* data = v8::ToCData<void*>(callback_info->data());
         callback(data);
       }
     }
   }
 }
 
 
+void Isolate::SetUseCounterCallback(v8::Isolate::UseCounterCallback callback) {
+  ASSERT(!use_counter_callback_);
+  use_counter_callback_ = callback;
+}
+
+
+void Isolate::CountUsage(v8::Isolate::UseCounterFeature feature) {
+  if (use_counter_callback_) {
+    use_counter_callback_(reinterpret_cast<v8::Isolate*>(this), feature);
+  }
+}
+
+
 bool StackLimitCheck::JsHasOverflowed() const {
   StackGuard* stack_guard = isolate_->stack_guard();
 #ifdef USE_SIMULATOR
   // The simulator uses a separate JS stack.
   Address jssp_address = Simulator::current(isolate_)->get_sp();
   uintptr_t jssp = reinterpret_cast<uintptr_t>(jssp_address);
   if (jssp < stack_guard->real_jslimit()) return true;
 #endif  // USE_SIMULATOR
   return reinterpret_cast<uintptr_t>(this) < stack_guard->real_climit();
 }
 
 
 } }  // namespace v8::internal