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

chrome/browser/plugin_process_host.cc

Index: chrome/browser/plugin_process_host.cc
diff --git a/chrome/browser/plugin_process_host.cc b/chrome/browser/plugin_process_host.cc
index 07ba6249b7790bdd72c7fd0deba33163ed06603e..d83324797d88937309f356651dffee869ed7747e 100644
--- a/chrome/browser/plugin_process_host.cc
+++ b/chrome/browser/plugin_process_host.cc
@@ -350,8 +350,8 @@ bool PluginProcessHost::Init(const WebPluginInfo& info,
   // 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;