Refactor PickleIterator.

chrome/browser/extensions/api/messaging/native_message_process_host_unittest.cc

Index: chrome/browser/extensions/api/messaging/native_message_process_host_unittest.cc
===================================================================
--- chrome/browser/extensions/api/messaging/native_message_process_host_unittest.cc	(revision 271871)
+++ chrome/browser/extensions/api/messaging/native_message_process_host_unittest.cc	(working copy)
@@ -142,10 +142,8 @@
 
  protected:
   std::string FormatMessage(const std::string& message) {
-    Pickle pickle;
-    pickle.WriteString(message);
-    return std::string(const_cast<const Pickle*>(&pickle)->payload(),
-                       pickle.payload_size());
+    uint32_t length = message.length();
+    return std::string(reinterpret_cast<char*>(&length), 4).append(message);
   }
 
   base::FilePath CreateTempFileWithMessage(const std::string& message) {