PrependWrapper is platform-specific, so it should take a platform string.

chrome/browser/plugin_process_host.cc

 // Copyright (c) 2010 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.
 
 #include "chrome/browser/plugin_process_host.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #elif defined(OS_POSIX)
 #include <utility>  // for pair<>
@@ skipping 332 matching lines @@
   info_ = info;
   set_name(UTF16ToWideHack(info_.name));
   set_version(UTF16ToWideHack(info_.version));
 
   if (!CreateChannel())
     return false;
 
   // Build command line for plugin. When we have a plugin launcher, we can't
   // allow "self" on linux and we need the real file path.
   const CommandLine& browser_command_line = *CommandLine::ForCurrentProcess();
-  std::wstring plugin_launcher =
-      browser_command_line.GetSwitchValue(switches::kPluginLauncher);
+  CommandLine::StringType plugin_launcher =
+      browser_command_line.GetSwitchValueNative(switches::kPluginLauncher);
   FilePath exe_path = GetChildPath(plugin_launcher.empty());
   if (exe_path.empty())
     return false;
 
   CommandLine* cmd_line = new CommandLine(exe_path);
   // Put the process type and plugin path first so they're easier to see
   // in process listings using native process management tools.
   cmd_line->AppendSwitchASCII(switches::kProcessType, switches::kPluginProcess);
   cmd_line->AppendSwitchPath(switches::kPluginPath, info.path);
 
@@ skipping 293 matching lines @@
     const std::vector<uint8>& data) {
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
 
   ChromePluginLib *chrome_plugin = ChromePluginLib::Find(info_.path);
   if (chrome_plugin) {
     void *data_ptr = const_cast<void*>(reinterpret_cast<const void*>(&data[0]));
     uint32 data_len = static_cast<uint32>(data.size());
     chrome_plugin->functions().on_message(data_ptr, data_len);
   }
 }