[wrapper-tracing] Add heap snapshot generator infrastructure

third_party/WebKit/Source/bindings/core/v8/V8PerIsolateData.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 149 matching lines @@
   void setThreadDebugger(std::unique_ptr<ThreadDebugger>);
   ThreadDebugger* threadDebugger();
 
   using ActiveScriptWrappableSet =
       HeapHashSet<WeakMember<ActiveScriptWrappableBase>>;
   void addActiveScriptWrappable(ActiveScriptWrappableBase*);
   const ActiveScriptWrappableSet* activeScriptWrappables() const {
     return m_activeScriptWrappables.get();
   }
 
+  class TemporaryScriptWrappableVisitorScope {
+    WTF_MAKE_NONCOPYABLE(TemporaryScriptWrappableVisitorScope);
+    STACK_ALLOCATED();
+
+   public:
+    TemporaryScriptWrappableVisitorScope(v8::Isolate* isolate,
+                                         ScriptWrappableVisitor* visitor)
+        : m_isolate(isolate) {
+      m_savedVisitor = currentVisitor(m_isolate);
+      swapInNewVisitor(visitor);
+    }
+    ~TemporaryScriptWrappableVisitorScope() {
+      swapInNewVisitor(m_savedVisitor);
+    }
+
+   private:
+    inline ScriptWrappableVisitor* currentVisitor(v8::Isolate* isolate) {
+      return V8PerIsolateData::from(m_isolate)->scriptWrappableVisitor();
+    }
+
+    void swapInNewVisitor(ScriptWrappableVisitor*);

[haraken, 2017/01/12 16:25:18]

Nit: swapInNewVisitor => setVisitor ?

(Swap sounds like it swaps the two visitors.)

[Michael Lippautz, 2017/01/13 15:08:40]

Done.

+
+    v8::Isolate* m_isolate;
+    ScriptWrappableVisitor* m_savedVisitor;
+  };
+
   void setScriptWrappableVisitor(
       std::unique_ptr<ScriptWrappableVisitor> visitor) {
     m_scriptWrappableVisitor = std::move(visitor);
   }
   ScriptWrappableVisitor* scriptWrappableVisitor() {
     return m_scriptWrappableVisitor.get();
   }
 
  private:
   explicit V8PerIsolateData(WebTaskRunner*);
@@ skipping 41 matching lines @@
   Vector<std::unique_ptr<EndOfScopeTask>> m_endOfScopeTasks;
   std::unique_ptr<ThreadDebugger> m_threadDebugger;
 
   Persistent<ActiveScriptWrappableSet> m_activeScriptWrappables;
   std::unique_ptr<ScriptWrappableVisitor> m_scriptWrappableVisitor;
 };
 
 }  // namespace blink
 
 #endif  // V8PerIsolateData_h