Don't send PP_Vars/V8 values with cycles across PostMessage

ppapi/tests/test_post_message.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PPAPI_TESTS_TEST_POST_MESSAGE_H_
 #define PPAPI_TESTS_TEST_POST_MESSAGE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 16 matching lines @@
   // Add a listener for message events which will echo back the given
   // JavaScript expression by passing it to postMessage. JavaScript Variables
   // available to the expression are:
   //  'plugin' - the DOM element for the test plugin.
   //  'message_event' - the message event parameter to the listener function.
   // This also adds the new listener to an array called 'eventListeners' on the
   // plugin's DOM element. This is used by ClearListeners().
   // Returns true on success, false on failure.
   bool AddEchoingListener(const std::string& expression);
 
+  // Posts a message from JavaScript to the plugin. |func| should be a
+  // JavaScript function which returns the variable to post.
+  bool PostMessageFromJavaScript(const std::string& func);
+
   // Clear any listeners that have been added using AddEchoingListener by
   // calling removeEventListener for each.
   // Returns true on success, false on failure.
   bool ClearListeners();
 
   // Wait for pending messages; return the number of messages that were pending
   // at the time of invocation.
   int WaitForMessages();
 
   // Verifies that the given javascript assertions are true of the message
@@ skipping 39 matching lines @@
 
   typedef std::vector<pp::Var> VarVector;
 
   // This is used to store pp::Var objects we receive via a call to
   // HandleMessage.
   VarVector message_data_;
 };
 
 #endif  // PPAPI_TESTS_TEST_POST_MESSAGE_H_