Add comments to document parameters of Dart_NativeEntryResolver.

runtime/include/dart_api.h

 /*
  * Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
  * for details. All rights reserved. Use of this source code is governed by a
  * BSD-style license that can be found in the LICENSE file.
  */
 
 #ifndef INCLUDE_DART_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
@@ skipping 2115 matching lines @@
 typedef void (*Dart_NativeFunction)(Dart_NativeArguments arguments);
 
 /**
  * Native entry resolution callback.
  *
  * For libraries and scripts which have native functions, the embedder
  * can provide a native entry resolver. This callback is used to map a
  * name/arity to a Dart_NativeFunction. If no function is found, the
  * callback should return NULL.
  *
+ * The parameters to the native resolver function are:
+ * \param name a Dart string which is the name of the native function.
+ * \param num_of_arguments is the number of arguments expected by the
+ *   native function.
+ * \param auto_setup_scope is a boolean flag that can be set by the resolver
+ *   to indicate if this function needs a Dart API scope (see Dart_EnterScope/
+ *   Dart_ExitScope) to be setup automatically by the VM before calling into
+ *   the native function. By default most native functions would require this
+ *   to be true but some light weight native functions which do not call back
+ *   into the VM through the Dart API may not require a Dart scope to be
+ *   setup automatically.
+ *
+ * \return A valid Dart_NativeFunction which resolves to a native entry point
+ *   for the native function.
+ *
  * See Dart_SetNativeResolver.
  */
 typedef Dart_NativeFunction (*Dart_NativeEntryResolver)(Dart_Handle name,
                                                         int num_of_arguments,
                                                         bool* auto_setup_scope);
 /* TODO(turnidge): Consider renaming to NativeFunctionResolver or
  * NativeResolver. */
 
 /*
  * ===========
@@ skipping 226 matching lines @@
  *
  * \param object An object.
  * \param peer A value to store in the peer field.
  *
  * \return Returns an error if 'object' is a subtype of Null, num, or
  *   bool.
  */
 DART_EXPORT Dart_Handle Dart_SetPeer(Dart_Handle object, void* peer);
 
 #endif  /* INCLUDE_DART_API_H_ */  /* NOLINT */