Add documentation for platform/bindings

third_party/WebKit/Source/platform/bindings/SharedPersistent.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:
  *
  *     * 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
@@ skipping 20 matching lines @@
 #ifndef SharedPersistent_h
 #define SharedPersistent_h
 
 #include "platform/bindings/ScopedPersistent.h"
 #include "platform/wtf/PassRefPtr.h"
 #include "platform/wtf/RefCounted.h"
 #include "v8/include/v8.h"
 
 namespace blink {
 
+// A ref counted version of ScopedPersistent. This class is intended for use by
+// ScriptValue and not for normal use. Consider using ScopedPersistent directly
+// instead.
 template <typename T>
 class SharedPersistent : public RefCounted<SharedPersistent<T>> {
   WTF_MAKE_NONCOPYABLE(SharedPersistent);
 
  public:
   static PassRefPtr<SharedPersistent<T>> Create(v8::Local<T> value,
                                                 v8::Isolate* isolate) {
     return AdoptRef(new SharedPersistent<T>(value, isolate));
   }
 
   v8::Local<T> NewLocal(v8::Isolate* isolate) const {
     return value_.NewLocal(isolate);
   }
 
   bool IsEmpty() { return value_.IsEmpty(); }
 
   bool operator==(const SharedPersistent<T>& other) {
     return value_ == other.value_;
   }
 
  private:
   explicit SharedPersistent(v8::Local<T> value, v8::Isolate* isolate)
       : value_(isolate, value) {}
   ScopedPersistent<T> value_;
 };
 
 }  // namespace blink
 
 #endif  // SharedPersistent_h