Track JS allocations as they arrive with no affection on performance when tracking is switched off

test/cctest/test-heap-profiler.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1987 matching lines @@
       heap_profiler->TakeHeapSnapshot(v8_str("snapshot"));
   CHECK(ValidateSnapshot(snapshot));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   const v8::HeapGraphNode* foo_func =
       GetProperty(global, v8::HeapGraphEdge::kProperty, "foo");
   CHECK_NE(NULL, foo_func);
   const v8::HeapGraphNode* code =
       GetProperty(foo_func, v8::HeapGraphEdge::kInternal, "code");
   CHECK_NE(NULL, code);
 }
+
+
+// This is an example of using checking of JS allocations tracking in a test.
+TEST(HeapObjectsTracker) {
+  LocalContext env;
+  v8::HandleScope scope(env->GetIsolate());
+  HeapObjectsTracker tracker;
+  CompileRun("var a = 1.2");
+  CompileRun("var a = 1.2; var b = 1.0; var c = 1.0;");
+  CompileRun(
+    "var a = [];"
+    "for (var i = 0; i < 5; ++i)"
+    "    a[i] = i;\n"
+    "for (var i = 0; i < 3; ++i)"
+    "    a.shift();\n");
+}