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

chrome/browser/gpu_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/gpu_process_host.h"
 
 #include "app/app_switches.h"
 #include "base/command_line.h"
 #include "base/thread.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 58 matching lines @@
     initialized_successfully_ = Init();
   }
   return initialized_successfully_;
 }
 
 bool GpuProcessHost::Init() {
   if (!CreateChannel())
     return false;
 
   const CommandLine& browser_command_line = *CommandLine::ForCurrentProcess();
-  std::wstring gpu_launcher =
-      browser_command_line.GetSwitchValue(switches::kGpuLauncher);
+  CommandLine::StringType gpu_launcher =
+      browser_command_line.GetSwitchValueNative(switches::kGpuLauncher);
 
   FilePath exe_path = ChildProcessHost::GetChildPath(gpu_launcher.empty());
   if (exe_path.empty())
     return false;
 
   CommandLine* cmd_line = new CommandLine(exe_path);
   cmd_line->AppendSwitchASCII(switches::kProcessType, switches::kGpuProcess);
   cmd_line->AppendSwitchASCII(switches::kProcessChannelID, channel_id());
 
   // Propagate relevant command line switches.
@@ skipping 120 matching lines @@
 
 URLRequestContext* GpuProcessHost::GetRequestContext(
     uint32 request_id,
     const ViewHostMsg_Resource_Request& request_data) {
   return NULL;
 }
 
 bool GpuProcessHost::CanShutdown() {
   return true;
 }